JP2015222308A - Imaging apparatus and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus configured to reduce standby time of a user when process control and imaging processing are executed simultaneously, and an image forming apparatus.SOLUTION: An imaging apparatus includes: an image carrier for carrying developer; a charging device for charging the image carrier; an exposure device for forming an electrostatic latent image on the charged image carrier; a developing device which causes the image carrier to carry the developer, on the basis of the electrostatic latent image formed on the image carrier; and a control device for periodically executing process control for stabilizing image quality. The control device calculates a predicted amount of change in image quality, on the basis of the number of sheets for jobs to be processed, and the current amount of change in image quality based on a value set in the previous process control, and determines priority as to whether to execute process control or imaging processing when the process control and the imaging processing are to be executed simultaneously.

Description

  The present invention relates to an image forming apparatus using an electrophotographic method and an image forming apparatus equipped with the image forming apparatus.

  Conventionally, a copying machine, a printer, a facsimile, or a multifunction machine functionally equipped with these is equipped with an image forming apparatus using an electrophotographic system that forms an electrostatic latent image by charging and exposing an image carrier. It has been known.

  In addition, in such an image forming device, by performing process control such as charge potential control and exposure amount control, an image with stable image quality can be obtained regardless of changes in temperature and humidity conditions or aging deterioration of the image carrier or the like. What was formed is already known (for example, refer to Patent Document 1).

  In this process control, in each apparatus arranged in the order of the image forming process of charging / exposure / development, a potential sensor is provided between the exposure apparatus and the developing apparatus to detect the surface potential of the latent image on the image carrier. Used.

  Based on the detection result of the potential sensor, the control device using the microprocessor mounted on the image forming device or the image forming device adjusts the charging potential of the charging device to a predetermined value, and then adjusts the exposure amount. By executing the control, the stability of the image quality is maintained.

  In addition, when a two-component developer composed of a toner and a carrier is used as a developer to be carried on the image carrier, the control device includes, in addition to charging potential control and exposure amount control, as a process control. Toner density control is performed.

  As described above, in the electrophotographic developing device, the charge amount of the developer changes due to a change in temperature and humidity or aged deterioration. In particular, in a developing device using a two-component developer, new toner is replenished to the developer in accordance with a decrease in the toner concentration of the developer due to toner consumption. With this replenishment, the carrier is repeatedly operated by stirring or the like. The toner is deteriorated by applying stress, and the charge amount of the toner changes.

  Specifically, when the image forming frequency of the high image area ratio is high, the charge amount of the toner is reduced by degrading the carrier by a phenomenon called spent that causes the toner component to adhere to the surface of the carrier particles.

  On the other hand, when the image forming frequency of the low image area ratio is high, the coat film on the surface of the carrier particles is scraped, the frictional resistance with the toner is increased, and the charge amount of the toner is increased. Therefore, if the amount of charge of the toner is too large, the image density is insufficient due to the excessive electrostatic adhesion between the toner and the carrier.

  Therefore, in the toner density control when using the two-component developer, the control device detects the potential due to writing of the reference pattern by the potential sensor, and sets the developing bias for the developing device at the time of creating the reference pattern according to the detected value. decide.

  By the way, in order to maintain image quality stability, it is desirable to execute process control at least once a day. In general, the process is performed when the main power supply is turned on and off at the start of work or when returning from the energy saving mode. Often controls are executed.

  However, when the user first turns on the main power, for example, it is often during printing or copying when a job processing command is output from a personal computer. In such a case, since the image forming process is not immediately executed, the user is put on standby from the execution of the process control to the completion of the image forming process in front of the image forming apparatus.

  The present invention has been made in order to solve the above-described problems. In the case where the execution timing of process control and the execution timing of image forming processing overlap, an operation that can shorten the waiting time of the user. An object is to provide an image device and an image forming apparatus.

  In order to achieve the above object, an image forming apparatus according to the present invention forms an electrostatic latent image on an image carrier that carries a developer, a charging device that charges the image carrier, and the charged image carrier. An exposure apparatus that carries the developer on the image carrier based on an electrostatic latent image formed on the image carrier, and a control device that periodically executes process control for stabilizing image quality And the control device uses a previous process time using a new use time of the image carrier and the charging device, and a temperature difference and a humidity difference between the time when the previous process control is executed and the current time. The amount of change in the current image quality based on the set value when control is executed is calculated, and when the process control execution timing overlaps with the image formation processing execution timing, The predicted change in image quality is calculated from the amount of change in image quality and the number of job processing outputs in the job processing command, assuming that image formation processing has been executed, and process control execution or image formation processing is performed according to the calculation result. It is the structure which determines the priority of execution.

  According to the present invention, it is possible to provide an image forming apparatus and an image forming apparatus that can shorten the waiting time of the user when the execution timing of the process control and the execution timing of the image forming process overlap.

It is explanatory drawing of the image forming apparatus which concerns on one embodiment of this invention. It is explanatory drawing of the control block in the image forming apparatus which concerns on one embodiment of this invention. FIG. 4 is a basic timing flowchart for executing process control in the image forming apparatus according to the embodiment of the present invention; It is a flowchart of the process control in the imaging device which concerns on one embodiment of this invention. It is a flowchart of the priority determination process routine which a control apparatus performs when the execution timing of process control and the execution timing of image formation processing overlap in the image formation apparatus which concerns on other embodiment of this invention.

  Next, an embodiment according to the present invention will be described with reference to the drawings. In the following embodiment, a monochrome printer is described as an example of an image forming apparatus equipped with the image forming apparatus of the present invention. However, a full-color machine can also be used, and can be applied to a copying machine, a facsimile machine, a multifunction machine, or the like. Is also possible.

  As shown in FIG. 1, a printer 10 as an image forming apparatus according to an embodiment of the present invention includes a paper feeding device 20, a registration roller pair 30, an image forming device 40, and a transfer device inside a printer main body 11. The apparatus 50, the fixing device 60, and the paper discharge device 70 are included.

  The printer main body 11 includes a paper feed cassette 12, a transport path 13, a reverse path 14, a paper discharge tray 15, and an operation panel unit 16 as a setting device.

  The paper feed cassette 12 is disposed in the lower part of the printer main body 11 and is housed so as to be drawable from the front (right side in FIG. 1) of the printer main body 11. A sheet-like recording material P can be stored in the paper feed cassette 12.

  In the conveyance path 13, a registration roller pair 30, an image forming device 40, a transfer device 50, a fixing device 60, and a paper discharge device 70 are arranged from the upstream end in the order of conveyance of the recording material P.

  The reverse path 14 is for performing image forming processing (hereinafter also referred to as “job processing”) on the back side of the recording material P, and joins from the downstream side of the fixing device 60 to the upstream end of the transport path 13. Forming a pathway. The reversing path 14 reverses the front and back of the recording material P by switching the recording material P that has undergone job processing to the front side by the paper discharge device 70 and then rejoining the recording material P at the upstream end of the conveying path 13.

  The transport path 13 and the reversing path 14 are provided with a plurality of paper feed roller pairs and a plurality of various sensors including jam detection as necessary, but the description thereof is omitted here.

  The paper discharge tray 15 is also used as the upper surface of the printer main body 11, and is inclined upward from the upstream side (left side in the drawing) of the recording material P to the downstream side (right side in the drawing).

  Although not shown in detail, the operation panel unit 16 has various operation switches such as a touch panel type liquid crystal display panel, a switch such as a numeric keypad, a main power supply and a switch for returning to the standby mode on the surface as an operation unit 16A described later. I have. Further, the operation panel unit 16 includes a control device (control circuit) 80 to be described later for executing the print function of the printer 10. The specific configuration and function of the control device 80 will be described later.

  The paper feeding device 20 includes a pickup roller 21, a separation roller pair 22, and a paper feeding path 23.

  The pickup roller 21 takes out the uppermost recording material P provided in the paper feed cassette 12.

  The separation roller pair 22 conveys the recording material P taken out by the pickup roller 21 to the paper feed path 23. At this time, the separation roller pair 22 separates the uppermost recording material P and the subsequent recording materials P so that only the uppermost recording material P among the recording materials P taken out by the pickup roller 21 is conveyed. It is like that. In the present embodiment, the separation roller pair 22 includes a normal rotation roller 24 and a reverse rotation roller 25 that rotate so as to be in opposite directions with respect to the nip portion, as indicated by arrows in FIG.

  The normal rotation roller 24 is positioned on the upper side and rotates in a direction in which the uppermost recording material P is fed out with respect to the nip portion. The reverse rotation roller 25 is positioned on the lower side and rotates in a direction to return the recording material P after the uppermost position with respect to the nip portion. The reverse roller 25 may be a simple pad member.

  The paper feed path 23 joins the upstream end in the transport direction of the recording material P in the transport path 13 provided in the printer main body 11, and the uppermost recording material P separated by the separation roller pair 22 is transferred to the transport path 13. And carry.

  The registration roller pair 30 abuts the downstream end of the conveyed recording material P to correct skew conveyance, and instantaneously stops the conveyance of the recording material P to perform timing alignment with the image forming device 40.

  The image forming apparatus 40 includes an image carrier 41 that carries a developer using a drum-shaped photoconductor. Further, the image forming apparatus 40 includes a charging device 42, an exposure device 43, a potential sensor 44, a developing device 45, a cleaning device 46, and a charge eliminating device 47 in the order of the image forming process around the image carrier 41. In addition, the image forming device 40 includes a toner density sensor 48 using a reflective photosensor or the like for detecting the toner density around the image carrier 41 and between the transfer device 50 and the cleaning device 46.

  The charging device 42 uniformly charges the surface of the image carrier 41, the cleaning device 46 removes residual toner, paper dust, and the like remaining on the image carrier 41, and the charge eliminating device 47 next removes the surface of the image carrier 41. The charge is uniformly removed for the image forming process. The charging device 42, the cleaning device 46, and the charge eliminating device 47 can use known techniques, and thus detailed description thereof is omitted here.

  The exposure device 43 writes an electrostatic latent image by irradiating the surface of the image carrier 41 between the charging device 42 and the developing device 45 with a laser beam L. The exposure apparatus 43 includes, for example, a light source 43a such as a laser diode that is driven based on image data included in a job processing command output from a personal computer (hereinafter simply referred to as “PC”). The laser beam L emitted from the light source 43a is deflected by a polygon mirror 43b that rotates at high speed, and optical scanning is performed on the surface of the image carrier 41 by an imaging lens 43c and a reflection mirror 43d to perform optical writing (exposure). . Further, since the exposure device 43 performs sub-scanning by rotating the image carrier 41 around the drum axis in addition to the main scanning by the laser beam L, a two-dimensional latent image is formed on the surface of the image carrier 41. create.

  In addition to the image data of the image forming process itself, the job processing command output from the PC includes various conditions set by the PC printing properties, such as the number of pages, the number of copies, the type of recording material, the designation of image quality, Various data such as enlargement / reduction and aggregation are included.

  The potential sensor 44 detects the surface potential of the image carrier 41 between the position where writing with the laser light L of the exposure device 43 is performed and the developing device 45 in order to properly operate the electrophotographic process.

  The developing device 45 includes a hopper 45 a that contains a replenishing developer, a pair of conveying screws 45 b and 45 c that circulate and convey the developer replenished from the hopper 45 a along the axial direction, and a surface of the image carrier 41. And a developing roller 45d for supplying the developer.

  The transfer device 50 includes a transport belt 51 that transports the recording material P, at least a pair of rollers 52 and 53 that rotate the transport belt 51 in a tension state, and a transport belt 51 at a transfer position that faces the image carrier 41. And a charger 54 for applying a transfer bias from the back surface of the battery.

  The fixing device 60 includes, for example, an internal heating type or external heating type fixing roller 61, a pressure roller 62 that presses the fixing roller 61, and a thermistor 63 that detects the surface temperature T of the fixing roller 61. The fixing device 60 fixes the toner image transferred onto the recording material P to the recording material P. The toner image transferred onto the recording material P is thermocompression bonded by heating the fixing roller 61 and pressing the pressure roller 62. To fix the toner image. The thermistor 63 detects the surface temperature T of the fixing roller 61 in order to manage the heating temperature for the fixing roller 61.

  The paper discharge device 70 has a driving roller 71 and a driven roller 72. For example, when the recording material P is nipped while the driving roller 71 is rotating in the counterclockwise direction in the drawing, the paper discharge device 70 discharges the recording material P toward the paper discharge tray 15. Further, for example, when the recording material P is nipped while the driving roller 71 is rotating in the clockwise direction in the drawing, the paper discharge device 70 switches back the recording material P.

  Here, an image forming process (job process) operation on the recording material P will be briefly described. Note that the image forming process from the feeding of the recording material P to the paper discharge described below is step S4 described later.

  Upon receiving a job processing command output from a PC or the like (not shown), the control device 80 controls all operations of the printer 10, that is, the entire printer operation up to image output by the print engine, and includes job processing including image forming processing. The start command is output to each part. Each unit that has received this start command, for example, starts driving the polygon mirror 43b, the image carrier 41, the fixing roller 61, and the like of the exposure device 43, and at the same time, starts processing the sent image data.

  Based on the image data, the control device 80 develops, for example, bitmap data as an image format, operates the exposure device 43 using the bitmap data, and performs laser writing on the image carrier 41.

  In the image carrier 41, an electrostatic latent image is generated by writing with the laser beam L from the exposure device 43 on the surface of the image carrier 41 uniformly charged by the charging device 42.

  A developer is attached to the electrostatic latent image by the developing device 45 to be visualized, and the obtained toner image is transferred to the recording material P of the transfer device 50 that is disposed opposite to the image carrier 41. .

  The recording material P on which the toner image is formed is sent to the fixing device 60 and discharged from the paper discharge device 70 to the paper discharge tray 15 after fixing processing by thermocompression bonding.

  By the way, the control device 80 suppresses the influence of environmental fluctuations and temporal fluctuations in the image forming operation, and stabilizes the image quality, in order to stabilize the image quality such as potential control and exposure amount control in the electrostatic latent image generation and image forming process. Perform process control.

  For this process control, a potential sensor 44 that detects the surface potential of the image carrier 41 is used. The control device 80 adjusts the exposure amount so that the potential after writing (exposure) by the exposure device 43 becomes a predetermined value after adjusting the charging potential by the charging device 42 to a predetermined value. Stabilize.

  When job processing is performed using a two-component developer, toner density control is performed as process control performed in accordance with the above adjustment.

  In this case, the control device 80 detects the surface potential of the image carrier 41 by writing the reference pattern with the potential sensor 44, and determines the developing bias at the time of creating the reference pattern according to the detected value.

  However, it takes a certain amount of time to execute process control. That is, the control device 80 starts heating the fixing device 60 simultaneously with the execution of the process control. After the process control is finished and the fixing device 60 reaches a predetermined fixing temperature (or the vicinity thereof), the recording material P is heated. Other job processing including the start of conveyance is started.

  At this time, the process control execution time is usually longer than the time required for the fixing device 60 to reach a predetermined fixing temperature.

  On the other hand, in recent years, the time required for the fixing device 60 to reach a predetermined fixable temperature is shorter than the process control execution time in response to high-speed startup.

  However, even if the time required for the fixing device 60 to reach the predetermined fixing temperature is shortened, the user still has a long time regarding the case where the execution timing of the process control and the execution timing of the image forming process overlap. Was forced to wait.

  Therefore, in this embodiment, even when the execution timing of process control and the execution timing of image forming processing overlap, the waiting time of the user can be shortened.

  FIG. 2 is an explanatory diagram of a control block of the printer 10 for realizing the shortening of the standby time.

  In FIG. 2, the control device 80 includes a CPU 81, a ROM 82, and a RAM 83. The control device 80 is constructed so that the process control processing according to the present embodiment can be executed using the CPU 81 which is a microprocessor.

  The CPU 81 reads out the image processing program from the ROM 82 and loads it into a part of the RAM 83 for the work area, and executes the image processing program using the other part of the RAM 83 as a work area. The CPU 81 receives a job processing command output from the PC and stores the job processing command in the RAM 83. The CPU 81 executes process control using the process control program according to the present invention.

  The ROM 82 and the RAM 83 store an image processing program that causes the CPU 81 to function as the printer 10. That is, each function of the printer 10 is executed by the CPU 81 that executes the image processing program.

  The control device 80 receives, as an input side, output signals from various sensors 17 disposed in the operation unit 16A such as a liquid crystal display panel and various operation switches provided in the operation panel unit 16, the transport path 13, and the reverse path 14. The The control device 80 includes an interface (I / F) 83 that receives an output signal from a PC or the like, a number counter 84, a timer 85 that measures the date and time when the recording material P and various devices are replaced, the temperature inside the printer main body 11, and the like. A temperature / humidity sensor 86 for detecting humidity is provided.

  The number counter 84 counts the number of processed jobs of the recording material P that has undergone image forming processing. At this time, for example, the recording material P of A4 standard size and the recording material P of A3 standard size can be counted separately. That is, regardless of the size, it is not simply counted as one sheet. For example, with the A4 standard size as a reference, the A4 standard size is counted as one sheet, and the A3 standard size is 2 sheets. You may count it as a sheet.

  Further, the number counter 84 may set a high, medium, and low level of the area ratio with respect to the image formable area excluding the margin of the recording material P, and may count the number of sheets according to the level. That is, even if the recording material P has the same A4 standard size, the case where only simple characters having no pattern or the like are formed on all pages of the paper size is considered to be in the area ratio, and the case including the pattern such as a photograph is high The area ratio can be reduced when only the sheet size is formed to be about half a page size. Furthermore, this area ratio high / low is converted into the number of jobs processed and replaced so that the medium area count is 1, the area ratio high is 1.5, and the area ratio low is 0.5. Is also possible.

  Further, the number counter 84 may count the job processing time, that is, the sheet passing time, in addition to counting the number of jobs processed for the recording material P. As a result, for example, the total sheet passing time can be used as a determination criterion without separately counting the A4 standard size and the A3 standard size.

  Note that the user can freely select or change the set value of the number of processed jobs for the recording material P on which the process control is executed, using the operation unit 16A in accordance with the usage state of the printer 10. Accordingly, for example, when job processing with a large image area ratio is frequently performed or when a large amount of A3 standard size recording material P is used, the setting of the number of job processing sheets to be a predetermined value determined by the control device 80 is reduced. Thus, the process control can be executed with an appropriate use frequency or degree of deterioration.

  On the other hand, the control device 80 receives detection signals from the potential sensor 44 and the toner density sensor 48 of the image forming device 40 in addition to the above-described inputs.

  Based on these input signals, the control device 80 controls the drive motor 87 such as each part drive roller in addition to the image forming device 40, the transfer device 50, and the fixing device 60.

  Next, process control executed by the control device 80 will be specifically described. FIG. 3 is a flowchart of a check routine for determining whether or not to execute process control by the control device 80 (abbreviated as “procon” in the figure).

  In step S1, the control device 80 causes the thermistor 63 to detect the surface temperature T of the fixing roller 61 when the main power is turned on or when returning from the standby mode (energy saving mode), and obtains the detected value. Then, the process proceeds to step S2.

  In step S2, the control device 80 determines whether or not the surface temperature T is a predetermined temperature, for example, 100 ° C. or higher (T ≦ 100 ° C.), and determines that the surface temperature T is equal to or higher than the predetermined temperature ( In Yes), the process proceeds to step S3. On the other hand, if the control device 80 does not determine that the surface temperature T is equal to or higher than the predetermined temperature (No), the routine ends.

In step S3, the control device 80 executes process control. In addition, as a control change content by the process control which the control apparatus 80 performs, specifically, as shown below,
(1): Change of color mode (2): Change of recording speed (3): Change of number of halftone lines (4): Change of halftone processing method (5): Restriction of paper type (6): Registration Control parameter change (7): There is an image forming process parameter change or the like. However, it is not necessary to execute all of them depending on the model or function of the printer 10.

  Further, (7) image forming process parameter changes executed by the control device 80 include, in the case of the electrophotographic image forming device 40, a charging potential, an exposure amount, a developing bias, a transfer bias, and the like.

  Further, the set values of (1) to (7) become the remaining floor set values when the next process control is executed.

  As described above, the surface temperature T of the fixing roller 61 is detected when the main power is turned on or when returning from the energy saving mode, and the surface temperature T is low (T ≦ 100 ° C.) before the job processing is ready. Process control is executed when the control device 80 determines that it is in the state. Thereby, for example, the process control can be executed at least once on business days.

  FIG. 4 is a flowchart of a specific routine of process control by the control device 80 described above.

  In step S11, the control device 80 calibrates the potential sensor 44 so that the detection value of the potential sensor 44 becomes a predetermined value when the reference voltage is applied to the image carrier 41, and the process proceeds to step S12.

  In step S12, the controller 80 calibrates the toner density sensor 48 that detects the reference pattern density of the image carrier 41, and proceeds to step S13. That is, the control device 80 adjusts so that the output of the toner density sensor 48 when the toner image is not formed on the image carrier 41 becomes a predetermined value (for example, 4V).

  In step S13, the control device 80 applies a predetermined grid voltage VG in the charging device 42, and proceeds to step S14.

  In step S14, the control device 80 detects the surface potential VD of the image carrier 41 when applied in step S13 by the potential sensor 44, and proceeds to step S15.

  In step S15, the control device 80 determines whether or not the surface potential VD of the image carrier 41 detected in step S14 is a target value within a predetermined range, for example, −900 ± 15 (V). If the controller 80 determines that the surface potential VD of the image carrier 41 is a target value within a predetermined range (YES), the controller 80 proceeds to step S16. On the other hand, if the control device 80 does not determine that the surface potential VD of the image carrier 41 is a target value within a predetermined range (NO), the control device 80 proceeds to step S17.

  In step S17, since the control device 80 did not determine that the target value was set in step S15, the control device 80 performs adjustment to add-(VD + 900) to the grid voltage VG, and then loops to step S14. Thereafter, this loop is repeated until the detected value reaches the target value of −900 ± 15 (V).

  In step S <b> 16, since the control device 80 determines that the surface potential VD of the image carrier 41 is the target value, the exposure device 43 adjusts the exposure amount. Specifically, the control device 80 forms the reference pattern latent image on the image carrier 41 with the light amount when the duty ratio in the PWM control of the laser diode (LD) 43a is 50%, and proceeds to step S18.

  In step S18, the control device 80 detects the surface potential VH at this time, and proceeds to step S19.

  In step S19, the control device 80 determines whether or not the detected value of the surface potential VH of the image carrier 41 detected in step S18 is a target value within a predetermined range, for example, −320 ± 20 (V). If the controller 80 determines that the surface potential VH of the image carrier 41 is a target value within a predetermined range (YES), the controller 80 proceeds to step S20. On the other hand, if the control device 80 does not determine that the surface potential VH of the image carrier 41 is a target value within a predetermined range (NO), the control device 80 proceeds to step S21.

  In step S21, since the control device 80 did not determine that the target value was reached in step S19, the light amount of the light source 43a was adjusted, and the detected value of the surface potential VH of the image carrier 41 became a target value within a predetermined range. Repeat this loop until

  In step S20, the control device 80 finishes the adjustment when it determines that the target value is within the predetermined range, determines that value as the light amount value, and ends this routine.

  As described above, the control device 80 performs process control when the main power is turned on or when returning from the energy saving mode, and after the process control is finished, the adjusted grid voltage VG of the charging device 42 and the exposure device 43 are adjusted. Image forming processing is executed with the exposure amount.

  Accordingly, adjustments are made with respect to changes in the environment and changes over time, and a stable and good-quality image can be formed.

  Next, a priority determination routine for determining the priority of process control execution or job processing execution by the control device 80 according to the present embodiment will be described with reference to FIG.

  In step S31, the control device 80 determines whether it is time to execute process control. That is, the control device 80 determines whether or not the main power is turned on or when returning from the energy saving mode, and if it is determined that the main power is turned on or when returning from the energy saving mode (YES), a step is performed. The process proceeds to S32. On the other hand, if the control device 80 does not determine that the main power supply is turned on or a return from the energy saving mode (NO), the control device 80 continues to monitor this routine.

  By the way, the control device 80 according to the present embodiment sets the priority of which one of the process control execution timing and the job processing execution timing to be executed as a priority when the execution timing overlaps with the following condition. Is determined as a criterion.

  That is, the control device 80 obtains the amount of change in the current image quality with reference to the set value when the previous process control is executed. Further, the control device 80 calculates a predicted change amount of image quality when it is assumed that job processing has been executed from the current change amount of image quality and the number of job processing outputs included in the job processing command. Here, the number of job processing outputs is the number of recording materials P included in the job processing command to be subjected to job processing from now on, that is, the number of print pages multiplied by the number of print copies.

  As a result, if the control device 80 determines from the calculated predicted change amount of the image quality that there is no significant change in image quality even if the job processing is executed without executing the process control, the control device 80 executes the execution of the process control. Instead of before, it tries to make the start-up waiting time as short as possible.

  For example, the image carrier 41, which is a drum-shaped photoconductor, needs to increase the grid voltage VG necessary to obtain the target surface potential VD by charging the surface of the image carrier 41 as it is used.

  Further, since the efficiency of the charging device 42 that uniformly charges the surface of the image carrier 41 decreases as it is used, it is necessary to set the grid voltage VG larger in the time-lapse product than in the new product.

  Further, since the toner charging ability of the two-component developer decreases as it is used, the ability to develop the toner on the image carrier 41 changes as compared to when it is new.

  Further, the charging ability of the image carrier 41 and the charging ability of the toner vary depending on the temperature and humidity inside the printer main body 11.

  In step S <b> 32, the control device 80 executes determination condition acquisition processing for calculating the current amount of change in image quality. That is, the control device 80 uses the timer 85 to measure the usage time from the new image carrier 41 to the present time, the charging device 42 from the new time to the present time, the developer from the new time to the present time, Get each. Further, the control device 80 obtains the temperature and humidity inside the printer main body 11 when the previous process control measured by the temperature / humidity sensor 86 is executed and the current time. Further, the control device 80 obtains the number of processed images, that is, the number of processed jobs (number of processed jobs or sheet passing time) for the recording material P from the number counter 84.

  Next, in step S <b> 33, the control device 80 executes a current image quality change amount calculation process. That is, the control device 80 obtains the grid voltage VG necessary for obtaining the standard target surface potential VD from the usage time of the image carrier 41. Further, the control device 80 determines the predicted grid voltage VF by correcting the grid voltage VG based on the usage time of the charging device 42 and the temperature and humidity inside the printer main body 11. Further, the control device 80 obtains the development bias at the time of creating a standard reference pattern from the usage time of the developer. Further, the control device 80 compares the grid voltage VG when the previous process control is executed with the current predicted grid voltage VF, the development bias when the previous process control is executed and the current predicted development bias, respectively, The amount of change in image quality is calculated.

  In addition, when correcting the grid voltage VG to obtain the predicted grid voltage VF, the control device 80 uses a temperature difference and a humidity difference between the time when the previous process control inside the printer main body 11 is executed and the current time. The control device 80 can also calculate the current image quality change amount in consideration of the number of job processes counted by the number counter 84.

  Next, in step S34, the control device 80 calculates a predicted change amount of the image quality. That is, the control device 80 calculates the predicted change amount of the image quality when it is assumed that the job processing is executed from the current change amount of the image quality calculated in step S33 and the number of job processing outputs included in the job processing command. The process proceeds to step S35.

  In step S35, the control device 80 determines whether or not the startup priority mode is selected between the image quality priority mode and the startup priority mode by operating the operation unit 16A. When determining that the startup priority mode is selected, the control device 80 always shifts to step S4 to prioritize job processing, and then shifts to step S3 to execute process control later.

  Thereby, for example, the number of processed jobs is always small, and it can be useful for a user who wants to always shorten the start-up waiting time regardless of the image quality. On the other hand, if the control device 80 does not determine that the startup priority mode is selected, the control device 80 proceeds to step S36. The routine of step S35 may be performed immediately after the routine of step S31, that is, before the routine of step S32.

  In step S36, the control device 80 determines whether or not the predicted change amount of the image quality when it is assumed that the job processing calculated in step S34 is executed is equal to or less than a predetermined value. If the control device 80 determines that the predicted change amount of the image quality is equal to or less than the predetermined value (YES), the process proceeds to step S4 to prioritize job processing and then proceeds to step S3 to perform process control. Execute. On the other hand, if the control device 80 does not determine that the predicted change amount of the image quality is equal to or less than the predetermined value (NO), the process proceeds to step S3 to execute process control, and then proceeds to step S4 to execute the job. Execute the process.

  Note that the control device 80 also performs process control even when the number of job processes (number of processed jobs or sheet passing time) obtained from the sheet counter 84 independently of the calculated predicted change amount of image quality reaches a predetermined value or more. May be executed with priority.

  In addition, when the number of job processing outputs included in the job processing command is small (for example, the number of processed jobs is 1 to 3), the control device 80 gives priority to job processing without calculating the predicted change amount of image quality. May be executed.

  As described above, when it is determined that the influence on the image quality is small, the process control is executed after the job processing, so that the waiting time at the start-up can be reduced.

  As described above, the image forming apparatus 40 and the printer 10 as the image forming apparatus according to the present embodiment can reduce the waiting time of the user when the execution timing of the process control and the execution timing of the image forming process overlap. It can be shortened.

  By the way, the present invention is not limited to the above-described embodiments, and various technically modified forms are included in the technical scope of the claims without departing from the gist of the invention.

  For example, in the above-described embodiment, the image forming apparatus is described as having the monochrome image forming apparatus 40, but the present invention is not limited to this. Specifically, a full color image forming device, for example, four image forming devices of yellow (Y), magenta (M), cyan (C), and black (K) may be provided. In this case, the control device 80 executes process control independently for each image forming device.

  As described above, the image forming apparatus and the image forming apparatus according to the present invention can reduce the waiting time of the user when the execution timing of the process control and the execution timing of the image forming process overlap. The image forming apparatus using the electrophotographic method and an image forming apparatus equipped with the image forming apparatus are effective.

10 Printer (image forming device)
DESCRIPTION OF SYMBOLS 40 Image forming device 41 Image carrier 42 Charging device 43 Exposure device 44 Potential sensor 45 Developing device 50 Transfer device

JP 2000-330345 A

Claims (6)

An image carrier carrying a developer;
A charging device for charging the image carrier;
An exposure device for forming an electrostatic latent image on the image carrier after charging;
A developing device for carrying the developer on the image carrier based on an electrostatic latent image formed on the image carrier;
A control device that periodically executes process control for stabilizing image quality;
Have
The controller is
Based on the set time when the previous process control was executed using the time when the image carrier and the charging device were used from the new article, and the temperature difference and the humidity difference between the previous time and the current process control. Calculate the amount of change in current image quality,
Image quality when it is assumed that the image forming process was executed from the calculated amount of change in the current image quality and the number of job processing outputs of the job processing command when the process control execution timing and the image forming process execution timing overlap An image forming apparatus characterized in that a predicted change amount is calculated and a priority of execution of process control or execution of image forming processing is determined according to the calculation result. The controller is
When a two-component developer is used as the developer, an influence on image quality is predicted in consideration of a usage time from the new article in the image carrier, the charging device, and the developer. Item 2. The image forming apparatus according to Item 1. The controller is
3. The image forming apparatus according to claim 1, wherein execution of the image forming process is prioritized when the predicted change amount of the image quality is equal to or less than a predetermined value. The image forming apparatus according to claim 3, wherein a plurality of the predetermined values for determination by the control apparatus can be selected or changed. A setting device that selects an image quality priority mode that prioritizes image quality and a startup priority mode that prioritizes startup of image forming processing;
The controller is
5. The image forming apparatus according to claim 1, wherein execution of the image forming process is prioritized when the start-up priority mode is selected.   An image forming apparatus comprising the image forming apparatus according to any one of claims 1 to 5.

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