JP2007147782A - Method for controlling developing device, controller for developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve toner refreshing operation in which wasteful consumption of developer is restrained. <P>SOLUTION: A method includes: a step of forming a patch image for measurement in predetermined timing; a step of measuring the image density of the patch image for measurement; a stage for comparing the image density with reference patch image density being the image density of the patch image for measurement having the quality of an allowable limit formed on a predetermined image generating condition; and a step of forming the patch image for measurement on the image generating condition in the formation of the reference patch image and performing operation for forcibly consuming the developer when the image density is equal to or under the reference image density as a result of comparison. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for controlling a developing device used in an image forming apparatus such as a copying machine, a printer, and a FAX, and more particularly to a technique such as control of forced consumption of developer in the developing device.

  Conventionally, various image forming apparatuses such as an electrophotographic system, an ink jet recording system, and a thermal transfer recording system have been researched and developed. In particular, the electrophotographic system has recently been increasingly used because it can be increased in speed and converted into plain paper. Product development is progressing, and many products such as electrophotographic copying machines, printers, facsimiles, etc. are on sale.

  Furthermore, recently, multifunction peripherals equipped with all output terminals such as copiers, printers, and fax machines have become widely accepted in the market. Image forming apparatuses using an electrophotographic process are widely accepted as such network-compatible output terminals, and such apparatuses are required to maintain their functions for a long period of time.

  FIG. 10 shows an example of a conventional image forming apparatus for forming a monochrome image. The image forming apparatus 100 is provided with an image forming mechanism in the center thereof. The image forming mechanism includes a photosensitive drum 110, a charging device 120 disposed around the photosensitive drum 110, an exposure device 111, a developing device 130, a transfer roller 112, a cleaning blade 113, a cleaning roller 114, and a static eliminator (see FIG. Not shown). A fixing device 115 is disposed downstream of the photosensitive drum 110 in the sheet conveyance direction. A carry-out device 140 having a plurality of paper discharge rollers 141 is arranged further downstream of the fixing device 115 in the paper conveyance direction. A paper feeding unit 151 is provided at the lower part of the image forming mechanism, and a plurality of paper feeding rollers 152 are disposed downstream of the paper feeding unit 151 in the paper feeding direction. The roller 152 constitutes the carry-in device 150.

  The charging device 120 is installed above the photosensitive drum 110 and uniformly charges the photosensitive drum 110, and includes a charging roller 121 and a voltage applying unit 122. The voltage application unit 122 is connected to the charging roller 121 so as to apply a bias voltage obtained by superimposing a DC voltage and an AC voltage as a charging voltage.

  The exposure device 111 is a device for exposing and forming an electrostatic latent image on the photosensitive drum 1 based on the image data input from the image data input unit 160.

  The transfer roller 112 is a means for transferring the toner image formed on the photosensitive drum 110 onto a transfer material such as paper.

  The developing device 130 includes a developing container 131, a developer carrier provided in the developing container 131, a layer thickness regulating unit, and a spiral.

  The developer carrying member includes a cylindrical rotatable developing roller 132 and magnetic field generating members 133a to 133e that are fixedly arranged in a non-contact manner with the developing roller 132 provided inside the developing roller 132. The generating members 133a to 133e have a cylindrical outer shape provided radially about the shaft member 134, and the developing roller 132 rotates about the shaft member 134. The developing roller 132 is applied with a developing bias from a voltage applying unit (not shown), and the charged toner is caused to fly to the photosensitive drum 110.

  The layer thickness regulating means includes a shaft 135, a magnetic field generating member 136 attached to the center of the shaft 135, and a hollow sleeve-shaped shape holding member 137 provided so as to accommodate the magnetic field generating member 136 and the shaft 135. It has a cylindrical shape and is arranged in parallel with the developer carrier A. In the magnetic field generating member 136, the magnetic field generating member 136 is realized as a magnetic pole (permanent magnet). The magnetic field generating member 136 is configured such that the shape holding member 137 is not in contact with the magnetic field generating member 136 and faces the developing roller 132 via the shape holding member 137, so that toner directly adheres to the surface thereof. There is no.

  The spiral C is composed of a shaft 138a and a spiral blade 138b formed around the shaft 138a, and agitates the toner stored in the developing container 131 by rotating around the shaft 138a.

  The cleaning blade 113 is a means for cleaning deposits such as residual developer remaining on the photosensitive drum 110. The cleaning roller 114 abuts on the surface of the photosensitive drum 110 and has a buffer function for rubbing the surface, collecting toner, and discharging toner.

  The fixing device 115 is a device for fixing the transferred toner image on a sheet.

  The image data input unit 160 is realized as an interface that receives data input from an optical reading mechanism or an external device such as a PC, and is a means for obtaining image data that is a source of an electrostatic latent image generated by the exposure device 111.

  The image condition setting unit 170 is an interface that accepts user input from the outside. The image condition setting unit 170 enlarges an image transferred onto a recording medium to the control unit 139 of the image data input unit 160, the exposure device 111, and the developing device 130. This is a means for setting parameters such as reduction, shading.

  The power supply device 180 includes a photosensitive drum 110, a charging device 120, an exposure device 111, a developing device 130, a transfer roller 112, a fixing device 115, a static eliminator, a carry-out device 140, a carry-in device 150, an image data input unit 160, and an image. It is a means for supplying power to the condition setting means 170, and is connected to the above-mentioned means and devices by a power supply line and a control signal line (not shown).

  In the image forming apparatus having the above-described configuration, a two-component developer composed of toner and a carrier is included as a developer in the developing device 130, and the toner is rubbed to a predetermined polarity by frictional mixing of the toner and the carrier. The toner is charged (the carrier is charged with a polarity opposite to that of the toner), and the charged toner is held on the carrier by an electric suction force.

  The toner in the developer is consumed by being developed, replenished from the toner cartridge, and outputting the image, the toner in the developer will be replaced, but the so-called printing rate is low and therefore consumed. When an image with a small amount of toner is continuously output, the toner is replaced little by little in the developing device 130. As a result, the time during which one toner exists in the developing device 130 becomes longer, resulting in a longer period of time. Then, it is friction mixed with the carrier in the developing container 131.

  Thus, the toner in the developer that has been repeatedly rubbed and stirred for a long period of time becomes irregular in shape, uneven in particle size distribution, and improves the fluidity of the developer. External additives such as titanium oxide particles added separately for the purpose are embedded in the toner surface. As a result, deterioration such as a decrease in the fluidity of the developer may occur, and an image having a desired image quality may not be obtained.

  In particular, when printing a low-print image for a long period of time, a toner with a small toner particle size and a high charge amount tends to remain in the developing container 131, the image density is lowered, and a high-quality image can be maintained. Since the toner disappears and the amount of toner consumption decreases, the toner in the developing device is also susceptible to stress.

  As a countermeasure against such a problem when printing an image with a low printing rate, a toner refresh operation is performed by forcibly consuming toner in the developing machine at a predetermined timing and replenishing new toner. Those in which the particle size distribution is properly returned are known.

Here, the predetermined timing at which the toner refresh operation is performed is obtained on the assumption that an image with a low printing rate is formed. Specifically, the following method has been proposed. That is, the video integrated value per output image is measured, and the toner consumption calculated based on this is compared with a predetermined reference value, so that the toner refresh operation is performed when the reference value is exceeded ( For example, see Patent Document 1). There is also known a technique in which the area ratio per moving distance of the developer carrying member is detected and compared with a predetermined reference value as a trigger for executing the toner refresh operation (for example, Patent Document 2). See).
JP 2004-29209 A JP 2005-43388 A

  However, the toner refresh operation of the conventional developing device has the following problems.

  Each of the toner refresh operations described above focuses on the timing of forming an image with a low printing rate, which causes the toner in the developing device to stay for a long time and become overcharged. The information that is originally required for such determination is the degree of deterioration of the toner of the developer stored in the developing device 130. This is because the deterioration of the toner is caused by the developer staying in the developing container 131 for a long time. During normal image formation, an appropriate amount of developer is discharged, and a new developer is supplied from the toner cartridge correspondingly. This is because the developer in the developing container 131 is replaced, whereas such a cycle is hindered in image formation with a low printing rate.

  Calculation of parameters such as the printing rate is performed to indirectly estimate the amount of developer to be ejected, but is uniquely determined by the input image data and the image area rate. On the other hand, the degree of toner deterioration depends on individual differences in image forming apparatuses and differences in the environment in which they are placed, that is, differences in characteristics of components such as a developer carrier, variations in image forming conditions, and the effects of temperature and humidity. It fluctuates due to causes such as developer quality variation.

  At this time, even if the printing rate calculated by each of the above methods falls below the reference value, the degree of deterioration of the toner actually discharged from the developing device is smaller than the corresponding value. This is synonymous with the fact that the uniquely calculated printing rate is estimated to be excessively low even though the substantial printing rate becomes a large value that does not require the toner refresh operation. If such a determination continues, as a result, the toner refresh operation is performed more times than actually required. Such excessive toner refreshing operation wasted the developer consumption.

  The present invention has been made in view of the above problems, and provides a developing device control method, a developing device control device, an image forming device, and the like that can realize a toner refresh operation that suppresses wasteful consumption of developer. To do.

In order to achieve the above object, the first aspect of the present invention comprises a step of forming a developer image for measurement at a predetermined timing,
Measuring the image density of the developer image for measurement;
Comparing the image density with a reference image density that is an image density of a reference developer image having acceptable quality, formed under predetermined image generation conditions;
A step of executing a forced consumption operation of the developer when the image density is equal to or lower than the reference image density as a result of the comparison,
The measurement developer image is a developing device control method formed under image generation conditions in the formation of the reference developer image.

  In the second aspect of the present invention, the predetermined timing is a time point when the image forming apparatus forms a preset number of images or a time point when the developing device is driven for a predetermined time. This is a method for controlling the apparatus.

  The third aspect of the present invention is the developing device control method according to the first aspect of the present invention, wherein the predetermined timing is determined based on measurement of a printing rate relating to an image formed by the image forming apparatus.

  According to a fourth aspect of the present invention, there is provided the developing device control method according to the first aspect, wherein the amount of developer consumed in the forced consumption operation is determined based on the reference image density and the image density.

  According to a fifth aspect of the present invention, there is provided the developing device control method according to the first aspect, wherein the predetermined image forming condition is a condition based on a parameter that can be set to the image forming apparatus from the outside.

  A sixth aspect of the present invention is the control method for a developing device according to the first or fifth aspect of the present invention, wherein the predetermined image forming condition is a condition set at the time of manufacturing the image forming apparatus.

  A seventh aspect of the present invention is the developing device control method according to the first aspect of the present invention, wherein the predetermined timing is corrected according to a temperature and / or humidity in the vicinity of the developing device.

  An eighth aspect of the present invention is the developing device control method according to the first aspect of the present invention, wherein the reference image density or the image density is corrected according to a temperature and / or humidity in the vicinity of the developing device.

  According to a ninth aspect of the present invention, there is provided the developing device control method according to the third aspect of the present invention, wherein a value corresponding to a temperature and / or humidity near the developing device is used for the measurement of the printing rate.

The tenth aspect of the present invention includes a step of measuring a period required to form a predetermined amount of image;
Comparing whether the measurement period obtained by the measurement is a predetermined period or less, and
As a result of the comparison, the developing device control method of the first aspect of the present invention further includes a step of not performing the forced consumption operation when the measurement period is longer than the predetermined period.

  An eleventh aspect of the present invention is the developing device control method according to the tenth aspect of the present invention, wherein the predetermined value is corrected according to a temperature and / or humidity in the vicinity of the developing device.

A twelfth aspect of the present invention is a control device for a developing device that controls the operation of the developing device of an image forming apparatus having an image carrier and a developing device that forms a developer image on the image carrier. And
Image density measuring means for measuring the image density of the developer image;
Control means for controlling the operation of the developing device based on the image density measured by the image density means,
The control means includes
Control for forming a developer image for measurement in the developing device at a predetermined timing;
Control for the image density measuring means to measure the image density of the developer image for measurement;
The image density is compared with a reference image density that is an image density of a developer image for measurement having an acceptable quality formed under a predetermined image generation condition, and as a result of the comparison, the image density is the reference image density. If it is below, control to execute the forced consumption operation of the developer,
In the formation of the measurement developer image by the developing device, the control device of the development device forms the measurement developer image under image generation conditions in the formation of the reference developer image.

According to a thirteenth aspect of the present invention, there is provided an image forming apparatus comprising: an image carrier; a developing device that forms a developer image on the image carrier; and an image density measuring unit that measures an image density of the developer image. A developing device control device for controlling the operation of the developing device based on the image density measured by the image density means,
Control for forming a developer image for measurement in the developing device at a predetermined timing;
Control for the image density measuring means to measure the image density of the developer image for measurement;
The image density is compared with a reference image density that is an image density of a developer image for measurement having an acceptable quality formed under a predetermined image generation condition, and as a result of the comparison, the image density is the reference image density. If it is below, control to execute the forced consumption operation of the developer,
In the formation of the measurement developer image by the developing device, the control device of the development device forms the measurement developer image under image generation conditions in the formation of the reference developer image.

Further, the fourteenth aspect of the present invention further includes a measuring means for measuring a period required to form a predetermined amount of image,
A comparison is made as to whether or not the measurement period obtained by the measurement is equal to or shorter than a predetermined period, and if the measurement period is greater than the predetermined period, the forced consumption operation is not performed. Alternatively, the control device of the developing device of the thirteenth aspect of the present invention.

Further, the fifteenth aspect of the present invention is an image carrier,
A developing device for forming a developer image for transfer on the image carrier;
Image density measuring means for measuring the density of the developer image;
An image forming apparatus including a developing device control device according to a twelfth aspect of the present invention.

According to a sixteenth aspect of the present invention, there is provided an image carrier;
A developing device for forming a developer image for transfer on the image carrier;
An image forming apparatus including a developing device control device according to a thirteenth aspect of the present invention.

  According to a seventeenth aspect of the present invention, there is provided a step of forming a developer image for measurement at a predetermined timing in the method for controlling a developing device according to the first aspect of the invention, and measuring the image density of the developer image for measurement. Comparing the image density with a reference image density, which is an image density of a measurement developer image having acceptable quality formed under predetermined image generation conditions, and the measurement developer image, Forming a reference developer image under image generation conditions, and causing the computer to execute a forced consumption operation of the developer when the image density is equal to or lower than the reference image density as a result of the comparison It is a program.

  The 18th aspect of the present invention is a recording medium recording the program of the 17th aspect of the present invention, which is a recording medium that can be processed by a computer.

  According to the present invention as described above, it is possible to realize a toner refresh operation that suppresses wasteful consumption of developer.

  Hereinafter, embodiments of the present invention will be exemplarily described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to specific examples unless otherwise specified. Only.

(Embodiment 1)
FIG. 1 shows a configuration diagram of an image forming apparatus according to Embodiment 1 of the present invention. The image forming apparatus 200 of the present embodiment differs from the conventional example shown in FIG. 10 in that a reflected image density sensor 210 that measures the image density on the surface of the photosensitive drum 110 and a conventional control unit 139 are replaced with a reflected image. The difference is that it includes control means 220 that acquires measurement data from the density sensor 210 and controls the developing device 130 based on the measurement data. The control means 220 has a timer and a memory (not shown).

  In the above configuration, the image forming apparatus 200 corresponds to the image forming apparatus of the present invention, and the control unit 220 corresponds to the control unit of the present invention. The reflected image density sensor 210 corresponds to the image density measuring means of the present invention, and the control means 220 and the reflected image density sensor 210 constitute a developing device control apparatus of the present invention. The photosensitive drum 110 corresponds to the image carrier of the present invention.

  The operation of the image forming apparatus 200 having the above configuration will be described, and the operation of the control device of the developing device and the embodiment of the control method of the developing device will be described.

  The conventional toner refresh operation calculates the printing rate of the developer image formed on the photosensitive drum based on the image area rate of the image data that is the source of the developer image. As described above, the parameter that is originally necessary for whether or not the refresh operation is possible is the degree of deterioration of the toner of the developer in the developing device 130, and the printing rate is merely a parameter for indirectly grasping this. However, while the calculation of the printing rate is uniquely determined by the input image data and the image area rate, the actual degree of toner degradation varies depending on individual differences and the environment of the image forming apparatus. This does not appropriately reflect the timing of the toner refresh operation, and mainly causes a wasteful toner refresh operation.

  The present invention pays attention to this point, and directly determines the degree of toner deterioration as the density of the developer image actually formed on the photosensitive drum as the developer discharge destination. The timing is set. Accordingly, it is possible to always grasp the accurate developer discharge amount and execute the toner refresh operation at an appropriate timing regardless of individual differences or environments of the image forming apparatuses.

  First, as an preparation, the image forming apparatus operates the image forming mechanism in the manufacturing process or the like (immediately after completion, immediately before shipment, etc., and the image forming apparatus can normally operate), and the charging device 120, A developer image having a predetermined area is generated on the photosensitive drum 110 by the exposure device 111 and the developing device 130, and this is used as a patch image. The patch image does not need to be formed on the entire surface of the photosensitive drum 110, and may have an area necessary for the reflected image density sensor 210 to detect the density.

  At this time, the control unit 220 stores the operation state of each part of the image forming apparatus at the time of patch image formation in a built-in memory (not shown). Specifically, in the charging device 120, the bias voltage value of the voltage applying means 122 (for each DC component and AC component), in the exposure device 111, the voltage applied to the laser diode, and the value of the developing bias (DC component, AC component). Store for each component). In addition, each parameter (image enlargement / reduction ratio, density) set in the image condition setting unit 170 used when creating the patch image is also stored as an initial condition. Further, the image forming apparatus is configured so that the image forming conditions can be returned to the initial state (factory default state) when a reset instruction is given. The reset instruction is a return to the initial condition of all parameters input by the user via the image condition setting unit 170, and the operating state of all the units in the image forming apparatus such as the voltage applying unit 112. The latter is carried out during maintenance of the image forming apparatus by an engineer.

  By storing parameters that can be set to the image forming apparatus from the outside from these basic operating condition and image condition setting means 170, a patch image can be reproduced later under the same conditions as in the initial state. Keep it like that.

Next, the density of the patch image formed on the photosensitive drum 110 is measured by the reflected image density sensor 210. The measurement result is recorded in the memory as information paired with the initial condition of the image forming apparatus described above. A patch image created under these initial conditions is set as a reference patch image, and the density of the reference patch image is set as a reference image density _CO . Thus, the preparation is completed, and the image forming apparatus is in a state where it can be normally operated.

  Hereinafter, detailed description will be given with reference to the flowchart of FIG. Assuming that the image forming apparatus 200 is in a normal operation state, the control unit 220 of the developing device 130 constantly observes the operation time of the image forming time by a built-in timer. It is determined whether the image forming apparatus is in an operating state for a predetermined period as a predetermined timing (Step 1). If it is determined that the image forming apparatus is operating for a predetermined period or longer, the initial condition is read from the memory, After setting each part state of the image forming apparatus as an initial condition, control for creating a patch image is performed (Step 2). The patch image created at this time is set in the basic operation condition and image condition setting unit 170 in which each internal part is the same as the state in which the initial state of creating the reference patch image is reproduced, that is, at the time of creating the reference patch image. When the toner is not deteriorated, the reference patch image in the initial state should be reproduced. This is hereinafter referred to as a measurement patch image.

Next, when the measurement patch image is formed on the photosensitive drum 110, the reflection image density sensor 210 measures the density of the measurement patch image (Step 3). The measurement result of the measurement patch image is transferred to the control unit 220. When the control unit 220 obtains this as the image density C, the control unit 220 compares it with the previously stored reference image density C _O (Step 4).

The reference image density C _O is defined as an image density that gives acceptable quality of the developer image. When the image density C of the measurement patch image is lower than this, the image is deteriorated. The measurement patch image is formed with the same basic operating conditions and parameters of the image forming apparatus as the reference patch image. Therefore, the toner deterioration of the developer is estimated as the cause of the density reduction that does not depend on these settings. Will be.

Is determined in step4, when the image density C of the measurement patch image is determined equal to or less than the reference image density C _O as toner deterioration has occurred, the control unit 220 executes the toner refresh operation (Step5) . When the toner refresh operation ends (Step 6), the image forming apparatus returns to the development and image forming operations as normal operations. Normal operation continues until the next predetermined period.

On the other hand, if the image density C of the measurement patch image is determined as a reference image density C _O larger, the process returns to Step1 as not occurring toner deterioration, normal operation is performed until the next predetermined time period .

  As described above, according to the present embodiment, when the toner refresh operation is executed, after the reference patch image created in advance as a suitable condition and the image forming apparatus 200 are operated for a predetermined period, By comparing the densities of the measurement patch images formed under the same conditions, the deterioration of the toner in the developer is directly detected as an image density change.

  As a result, it is not affected by individual differences in the image forming apparatus or the environment in which the image forming apparatus is placed, that is, differences in the characteristics of the components such as the developer carrier, and variations in the quality of the developer due to the influence of temperature and humidity. The toner refresh operation can be executed at the timing.

  In the above description, the time period based on the timer built in the control unit 220 is taken as an example of the predetermined period serving as the execution trigger of Step 2, but the number of images formed by the image forming apparatus (one image) Step 2 may be executed when the predetermined number of sheets is reached.

  Further, in the above operation, a flow for shifting from Step 6 to Step 2 instead of Step 1 is provided, and after the toner refresh operation is once completed, a patch image for measurement is further created, and the density is measured and compared again. It may be determined whether or not the refresh operation is necessary. This has the effect of preventing the occurrence of toner that cannot be discharged by only one toner refresh operation when the toner is excessively charged.

Furthermore, based on the difference between the reference image density C _O and the image density C of the comparison in Step4, it may be set the forcible discharge amount of toner during the toner refresh operation. In this embodiment, since the degree of toner deterioration can be determined as the density difference, the operation efficiency of one toner refresh operation can be further increased.

Although reference image density C _O and toner amount difference discharging the larger the image density C had better high, as an example, the reference image density C _O as 1.30, the difference between the image density C is When it is less than 0.15, a solid image having a belt-like shape in which the circumferential width of the photosensitive drum 110 is 10 mm (the axial width of the photosensitive drum 110 is set as large as possible for image formation), 0.15 or more and 0.1. If it is less than 3, it is desirable to increase it to 20 mm, and if it is 0.3 or more, it is desirable to increase it to 30 mm.

(Embodiment 2)
The image forming apparatus 300 according to the second embodiment of the present invention shown in FIG. 3 is different from the first embodiment shown in FIG. 1 in that a known print rate is calculated by inputting image data from the image data input unit 160 and calculating the print rate. The measuring unit 230 is provided, and the control unit 220 of the developing device 130 is different in that it operates by acquiring the printing rate data 231 from the printing rate measuring unit 230. In FIG. 3, the same or corresponding parts are denoted by the same reference numerals, and detailed description thereof is omitted.

  Hereinafter, detailed description will be given with reference to the flowchart of FIG.

  The image forming apparatus 300 receives the input of image data from the image data input unit 160, and the exposure latent image generation on the photosensitive drum 110 by the exposure device 111 and each part of the image forming mechanism below the developing device 130 operate. At this time, similarly to the conventional example, when the image forming apparatus 300 forms a predetermined number of images (by user setting), the printing rate measuring unit 230 calculates the printing rate from the input image data corresponding to the number of image forming sheets. This is measured (Step 11), and this is output to the control means 220 of the developing device 130 as the printing rate data 231. This is a predetermined timing.

  When acquiring the printing rate data 231, the control unit 220 determines whether or not the printing rate data 231 is equal to or less than a predetermined value (Step 12). At this time, the predetermined value may be an arbitrarily determined value, but is preferably about 3% as an example.

  If the printing rate is greater than the predetermined value, the process returns to the step 11 and before, and the normal operation is continued.

  If the printing rate is equal to or less than the predetermined value, the control unit 220 proceeds to the measurement patch image forming operation (Step 13). Thereafter, in the same manner as in the first embodiment, the density measurement of the measurement patch image is performed. Based on the comparison with the reference image density, a determination is made as to whether or not the toner refresh operation is possible, and an operation based on the determination is performed (Steps 14 to 17). Note that Steps 13 to 17 in the second embodiment correspond to Steps 2 to 6 in the first embodiment, respectively.

  As described above, according to the present embodiment, the printing rate is measured when the measurement patch image forming operation that triggers the toner refresh operation as a predetermined timing is performed, and the determination result is used as a trigger. Like to do. Combining conventional printing rate measurement operations eliminates individual differences in image forming devices and differences in the environment that have been a hindrance to accurate timing judgments in judgments based on conventional printing rate measurements. Even if the rate measurement includes an error, the toner refresh operation can be executed at an appropriate timing. Further, by measuring the printing rate first, it is possible to prevent a measurement patch image from being wasted by setting the operation period and the number of formed images, and it is possible to determine the toner refresh operation more accurately. .

  In the above description, the measurement of the printing rate is the data amount per predetermined number of image formations, but data such as the image area rate per moving distance of the photosensitive drum 110 may be used.

(Embodiment 3)
FIG. 5 is an enlarged view of the vicinity of the image forming mechanism of the image forming apparatus according to the third embodiment of the present invention. The developing device of the present embodiment includes a humidity sensor 240 that is provided in the vicinity thereof and that measures the ambient humidity, and a temperature sensor 250 that uses a bimetal, a temperature-sensitive magnetic material, a semiconductor, and the like that measures the ambient temperature. Furthermore, the point provided is characterized.

  The environment in the vicinity of the developing device affects the toner of the developer. When the absolute humidity (the amount of moisture in the air) is higher than the appropriate value, the charged charge of the toner tends to be lost due to moisture, so that the image density becomes higher than necessary or so-called fog tends to occur. Further, in a very dry state where the absolute humidity is lower than an appropriate value, the toner tends to be excessively charged, which may cause a phenomenon such as a decrease in image density.

  On the other hand, the influence on the developer image due to the environment in the vicinity of the developing device is not linked to the deterioration of the toner based on stress, magnetization, etc. that require the toner refresh operation. When image degradation occurs, the image density of the measurement patch image measured by the reflected image density sensor 210 varies, and the accuracy of the relationship between the image density and the degree of toner degradation is lost.

  Therefore, in the control device of the developing device of the present embodiment, the humidity sensor 240 and the temperature sensor 250 measure the humidity in the vicinity of the photosensitive drum at the time of patch image creation. The humidity sensor 240 measures relative humidity, and the absolute humidity is obtained as a relationship between the temperature measured by the temperature sensor 250 and the temperature measured by the temperature sensor 250 at that time.

  The control means 220 stores each measurement result in a memory (not shown). That is, the measurement values of the temperature sensor 250 and the humidity sensor 240 (for example, the temperature is 23 ° C. and the humidity is 60%) are stored as one of the initial conditions at the time of creating the reference patch image, and similarly when measuring the patch image for measurement. The measured values of the humidity sensor 240 and the temperature sensor 250 are stored, and both measured values are compared with each measured value at the time of creating the reference patch image. It should be noted that the reference patch image is preferably created under temperature and humidity conditions in which the image forming apparatus operates favorably.

At this time, if the temperature and humidity at the time of creation of the measurement patch image are larger than the temperature and humidity at the time of creation of the reference patch image (for example, the temperature is 30 ° C. and the humidity is 80%), the control means 220 increases the magnitude. The image density of the measurement patch image is corrected according to the degree (difference, ratio, etc.). As an example, in the operation of Step 4 of Embodiment 1, when the temperature and humidity near the developing device 130 are large, the image density C of the measurement patch image is lower than the density at the appropriate time due to the reduction of the charged charge of the toner. The control unit 220 corrects the density C to C ′ = αC (α: a number satisfying 0 <α ≦ 1) and compares the correction value C ′ with the reference image density _CO to determine the toner. It is determined whether or not the refresh operation is appropriate. The constant α is a correction coefficient derived from the relationship between the temperature and humidity at the initial conditions and the temperature and humidity at the time of measuring the patch image for measurement.

  As described above, according to the present embodiment, the density of the measurement patch image is corrected and the toner is corrected even when the temperature and humidity in the vicinity of the developing device 130 increase in accordance with the location of the image forming apparatus. The execution of the refresh operation can be appropriately determined.

In the above operation, the description has been made assuming that the image density C is corrected in the comparison between the image density C of the measurement patch image and the reference image density _CO . However, the image density C is set as a fixed value. The image density _CO may be corrected. In this case, since the temperature and humidity of the initial conditions for creating the reference patch image are considered to be lower than the temperature and humidity at the time of creating the image density C, the reference image density C _O is set to be larger. The value is corrected to a reference image density C _O ′ having a value C _O ′ = βC _O (β: a number satisfying β <1).

  Further, using the detected temperature and humidity, the predetermined period (number of images formed) in Step 1 of Embodiment 1 may be corrected. When the temperature and humidity are high, the predetermined period is long, and when it is low, it is short.

  Further, it may be used for correcting a predetermined number of image formations in the measurement of the printing rate in the second embodiment. When the temperature and humidity are high, the predetermined period is long, and when it is low, it is short. Further, it may be used to correct the comparison value of the measured printing rate. When the temperature and humidity are high, the predetermined value is increased, and when the temperature and humidity are low, the predetermined value is decreased.

  Furthermore, instead of the correction, a predetermined value may be set for a plurality of predetermined periods according to humidity and temperature.

(Embodiment 4)
FIG. 6 shows the configuration of the image forming apparatus according to the fourth embodiment of the present invention. The same or corresponding parts as those in FIG. 3 of the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. The measuring unit 260 is a unit that measures the number of developer images formed by the developing device 130, and corresponds to the measuring unit of the present invention.

  The operation of the developing device 130 according to the present embodiment is characterized by further including a weighting requirement of a period required to form an image having a predetermined printing amount in the measurement of the printing rate.

  The printing rate measured in Step 11 of the second embodiment described above is the same as in the conventional example, after the image forming apparatus 300 (developing device 130) forms a predetermined number of images, the printing rate measuring unit 230 applies the printing rate. It was obtained by measuring from the amount of image data per predetermined number of images.

  However, even in such a printing rate measurement, although appropriate control can be normally executed without any problem, there may be a case where further correction is required in a special use environment.

  More specifically, an exceptional image formation in which 5000 sheets are printed per week, that is, only 500 sheets are printed per week in an average image forming apparatus that performs an operation of forming 5000 images. When the operation of significantly reducing the number of sheets may be performed, it is not necessary to perform the toner refresh operation even if the average printing rate during that time is below a predetermined value for determination. The reason is that if the printing interval is long, the charge held by the toner particles is gradually released during that time, and it is difficult to cause a decrease in density due to high charge.

  In the present exemplary embodiment, in consideration of such exceptional cases, a predetermined and precise determination of whether or not to perform a toner refresh operation according to the operation state of the image forming apparatus can be realized. The period required to form an image with the print amount is added to the requirement for determining whether or not the toner refresh operation is possible.

  Hereinafter, an explanation will be given with reference to the flowchart of FIG. 7, and an embodiment of a control device and control method for forced consumption of developer of the developing device of the present invention will be described.

  First, while the image forming apparatus continues the image forming operation by normal use, the measuring unit 260 measures the number of printed sheets (Step 21), and the control unit 220 determines whether the image forming has reached a predetermined number (for example, 1000). It is determined whether or not (Step 22). The number of printed sheets may be calculated from the driving time of the developing device 130.

When reaching the predetermined number, the control unit 220 calculates the internal timer time _{P x} required for image formation of the predetermined number (Step 23).

Next, the control means 220 determines whether or not the calculated time P _x is longer than a predetermined period P ₁ (one day as an example) (Step 24).

If the calculated period P _x is equal to or less than the predetermined period P _1, and sets a predetermined value criteria become printing ratio of whether the toner refresh operation in the same 3.0% normal (Step 25), the second embodiment After moving to Step 11, the same operation as in the second embodiment is performed up to Step 17 (Step 26).

On the other hand, longer than the predetermined period _{P 2,} to determine longer or not than a predetermined period _{P 2} (1 week as one example) (Step 27). If the calculated time period is equal to or less than the predetermined period _{P 2,} sets a predetermined value criteria become printing ratio of whether the toner refresh operation usually less than 2.0% (Step28), to Step11 embodiment 2 After that, the same operation as in the second embodiment is performed up to Step 17 (Step 26).

Furthermore, the calculated period is longer than the predetermined period _{P 2,} further predetermined period _{P 3} to determine longer or not than (for example 2 weeks) (STEP 29). If the calculated time period is equal to or less than the predetermined period _{P 3,} to set the predetermined value of the printing rate as a criterion of whether the toner refresh operation smaller than the normal 1.0% (Step30), Embodiment 2 Step11 Thereafter, the same operation as in the second embodiment is performed up to Step 17 (Step 26). On the other hand, the calculated period P _x is longer than the predetermined period P _3, it is determined that there is no need for toner refresh operation at this point, to return to Step21 previous state.

  In the above steps, the period required for printing is used on the basis of the printing amount. Instead, the comparison and control are performed based on the printing amount per unit time on the basis of the period required for printing. Good. Further, as the amount to be measured, the total driving time of the developing device may be used instead of the printing amount. In the case of the above operation, whether or not the toner refresh operation is possible and the reference of the printing rate are determined based on the length of the driving time of the developing device corresponding to the printing amount of 1000 sheets.

  As described above, according to the present embodiment, the printing rate measuring unit 230 calculates a period required to form an image having a predetermined printing amount, and if this is larger than the predetermined amount, the toner refresh operation is not executed. Thus, it is possible to reduce meaningless toner refresh operations and suppress consumption of the developer.

  Also, the printing rate that is a criterion for determining the toner refresh operation is appropriately changed according to the degree of time required to form an image with a predetermined printing amount. As a result, even in the conventional toner refresh operation using the printing rate, it is possible to make a specific and precise determination in accordance with the usage state of the image forming apparatus.

  Further, in combination with the humidity sensor 240 and the temperature sensor 250 of the third embodiment, a predetermined number of corrections and a predetermined value for comparison are corrected based on the measurement temperature and the measurement humidity. May be.

(Embodiment 5)
In each of the above embodiments, the image forming apparatus forms a monochrome image, but the developing device 130 of the present invention can also be realized in an image forming apparatus that forms a color image.

  FIG. 8 is a configuration diagram of an image forming apparatus according to the fifth embodiment of the present invention. However, the same or corresponding parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. The image forming apparatus 400 according to the present embodiment includes a developing device 310 that supplies four color developers and a transfer device 320 that transfers the developer image, instead of the developing device 130 according to the first embodiment.

  The developing device 310 includes a rotary rack 311 and a plurality of developing devices 312Y, 312M, 312C, and 312K. The rotary rack 311 rotates a plurality of developing units 312Y, 312M, 312C, and 312K in order to a developing position facing the photosensitive drum 1 while performing rotation by rotating about a shaft 313 by a rotating unit (not shown). is there. Among the plurality of developing devices, the yellow developing device 312Y, the magenta developing device 312M, the cyan developing device 312C, and the black developing device 312K are arranged and held in the circumferential direction of rotation of the rotary rack 311 in the order of Y, M, C, and K colors. Adjacent developing devices are arranged at intervals of about 90 degrees in the circumferential direction.

  The transfer device 320 is a device for transferring the developer image on the photosensitive drum 1 to a transfer material such as paper, and includes an intermediate transfer belt 321, a primary transfer roller 322, a driving roller 323, a secondary transfer counter roller 324, A secondary transfer roller 325 is provided. The intermediate transfer belt 321 is wound around the primary transfer roller 112, the driving roller 323, and the secondary transfer counter roller 324 in an endless manner, and is driven by the driving roller 323 so that the developer image formed on the photosensitive drum 110 is transferred. It serves as a transfer body that is transferred and temporarily held. The secondary transfer roller 325 is disposed on the outer peripheral surface of the intermediate transfer belt 321 at a position facing the secondary transfer counter roller 324, and transfers the developer image to the transfer material.

  In such an image forming apparatus, image formation is performed for each of the developing devices 312Y to 312K, and the developer images of yellow, magenta, cyan, and black are superimposed on the transfer belt 321 and transferred onto the intermediate transfer belt 321. Then, this is transferred onto a single transfer material, thereby forming a color developer image.

  Therefore, since a developer image is generated for each color, that is, for each developer, it is necessary to perform a toner refresh operation for each developer.

  Therefore, the control unit 220 performs the same control as in the first to fourth embodiments for each of the developing devices 312Y, 312M, 312C, and 312K. That is, formation of a reference patch image and measurement of image density, formation of a patch image for measurement and measurement of image density, measurement of printing rate data, measurement of temperature and humidity near the developing device 130, conversion of printing rate data into unit time equivalents These operations and operating conditions are performed independently for each of the developing devices 312Y, 312M, 312C, and 312K.

  Further, the color image forming apparatus transfers the developer images of yellow, magenta, cyan, and black onto the area on the intermediate transfer belt 321, and at this time, the density of each developer image is adjusted appropriately. Therefore, a reflection image density sensor for measuring the image density of the developer image is inherently provided.

  The developing device 130 according to the present embodiment can acquire data from the reflection image density sensor and measure the image density of the reference patch image and the measurement patch image. In this case, there is an advantage that the control device of the present invention can be realized as a configuration that does not have a separate image density measuring means. The arrangement of the reflection image density sensor may be the reflection image density sensor 330 directed on the surface of the intermediate transfer belt 321 shown in FIG. 8 or directed on the main surface of the photosensitive drum 110. An arrangement like the reflection image density sensor 340 may be adopted.

  FIG. 9 is a schematic diagram of a so-called tandem type image forming apparatus in which image forming mechanisms corresponding to the respective colors (black, yellow, cyan, magenta) are arranged in tandem on the intermediate transfer belt 321. The image forming mechanism is mainly composed of photosensitive drums 340a to 340d, charging devices 341a to 341d, and developing devices 342a to 342d provided for each color. The control unit 220 is an intermediate transfer belt of each image forming mechanism. The image density information is acquired from the reflected image density sensors 350a to 350d provided in front of the direction 321 (arrow in the figure), and it is determined whether or not the toner refresh operation is possible. In this image forming apparatus, by implementing the present invention, the reference patch image can be simultaneously formed for each developing device, and the initial conditions including the external environment of humidity and temperature can be made uniform for each developing device. There is an advantage.

  Note that the present invention is not limited to this, and only one reflection image density sensor may be provided at the position of 350a on the most downstream side. Each image has its image density measured when it moves to the most downstream position as the intermediate point transfer belt 321 advances. In this case, the cost can be reduced by reducing the number of sensors.

  The image forming apparatus according to each of the above embodiments can be used as a device such as a printer or a fax or other information processing apparatus. In short, as long as it is a device that transfers a developer image and obtains a copy image, the control device of the developing device and the image forming device of the present invention may be configured or implemented in any application device. May be.

  Further, the present invention is a program for causing a computer to execute the operation of all or part of the steps of the developing device control method of the present invention described above, and may be a program that operates in cooperation with the computer.

  Note that a part of the process of the present invention means some of the plurality of processes or a part of the operation of one process.

  Further, the present invention includes a computer-readable recording medium that records the program of the present invention.

  Further, one usage form of the program of the present invention may be an aspect in which the program is recorded on a computer-readable recording medium and operates in cooperation with the computer.

  Further, one usage form of the program of the present invention may be an aspect in which the program is transmitted through a transmission medium, read by a computer, and operated in cooperation with the computer.

  Further, the recording medium includes a ROM and the like.

The computer of the present invention described above is not limited to pure hardware such as a CPU, and may include firmware, an OS, and peripheral devices.
As described above, the configuration of the present invention may be realized by software or hardware.

  The developing device control method, the developing device control device, and the image forming apparatus according to the present invention have a special effect that a toner refresh operation that suppresses wasteful consumption of the developer can be realized. It is useful as an image forming apparatus such as FAX.

1 is a diagram illustrating a configuration of an image forming apparatus according to a first embodiment of the present invention. The figure which shows the control flowchart by the control means of the image development apparatus of Embodiment 1 of this invention. The figure which shows the structure of the image forming apparatus of Embodiment 2 of this invention. The figure which shows the control flowchart by the control means of the image development apparatus of Embodiment 1 of this invention. Enlarged view of the vicinity of the developing device in the image forming apparatus of Embodiment 3 of the present invention. The figure which shows the structure of the image forming apparatus of Embodiment 4 of this invention. The figure which shows the control flowchart by the control means of the developing device of Embodiment 4 of this invention. FIG. 10 is a diagram illustrating a configuration example of an image forming apparatus according to a fifth embodiment of the present invention. The figure which shows the other structural example of the image forming apparatus of Embodiment 5 of this invention. 1 is a diagram showing an example of a conventional image forming apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 110 Photosensitive drum 111 Exposure apparatus 120 Charging apparatus 130 Developing apparatus 140 Unloading apparatus 150 Loading apparatus 160 Image data input part 170 Image condition setting means 180 Power supply apparatus 210 Reflected image density sensor 220 Control means

Claims (18)

Forming a developer image for measurement at a predetermined timing;
Measuring the image density of the developer image for measurement;
Comparing the image density with a reference image density that is an image density of a reference developer image having acceptable quality, formed under predetermined image generation conditions;
A step of executing a forced consumption operation of the developer when the image density is equal to or lower than the reference image density as a result of the comparison,
The method for controlling a developing device, wherein the developer image for measurement is formed under image generation conditions in forming the reference developer image.   The developing device control method according to claim 1, wherein the predetermined timing is a time when the image forming apparatus forms a preset number of images or a time when the developing device is driven for a predetermined time.   The developing device control method according to claim 1, wherein the predetermined timing is determined based on measurement of a printing rate relating to an image formed by the image forming apparatus.   The developing device control method according to claim 1, wherein an amount of developer consumed in the forced consumption operation is determined based on the reference image density and the image density.   The developing device control method according to claim 1, wherein the predetermined image forming condition is a condition based on a parameter that can be set to the image forming apparatus from the outside.   The developing device control method according to claim 1, wherein the predetermined image forming condition is a condition set when the image forming apparatus is manufactured.   The developing device control method according to claim 1, wherein the predetermined timing is corrected according to a temperature and / or humidity in the vicinity of the developing device.   The developing device control method according to claim 1, wherein the reference image density or the image density is corrected according to a temperature and / or humidity in the vicinity of the developing device.   The developing device control method according to claim 3, wherein a value corresponding to a temperature and / or humidity near the developing device is used for the measurement of the printing rate. Measuring the time required to form a predetermined amount of image;
Comparing whether the measurement period obtained by the measurement is a predetermined period or less, and
2. The developing device control method according to claim 1, further comprising a step of not performing the forced consumption operation when the measurement period is longer than the predetermined period as a result of the comparison.   The developing device control method according to claim 10, wherein the predetermined value is corrected according to a temperature and / or humidity in the vicinity of the developing device. A developing device control device for controlling an operation of the developing device of an image forming apparatus having an image carrier and a developing device for forming a developer image on the image carrier;
Image density measuring means for measuring the image density of the developer image;
Control means for controlling the operation of the developing device based on the image density measured by the image density means,
The control means includes
Control for forming a developer image for measurement in the developing device at a predetermined timing;
Control for the image density measuring means to measure the image density of the developer image for measurement;
The image density is compared with a reference image density that is an image density of a developer image for measurement having an acceptable quality formed under a predetermined image generation condition, and as a result of the comparison, the image density is the reference image density. If it is below, control to execute the forced consumption operation of the developer,
In the formation of the measurement developer image by the developing device, the control device for the development device forms the measurement developer image under image generation conditions in the formation of the reference developer image. The image density means of an image forming apparatus comprising: an image carrier; a developing device that forms a developer image on the image carrier; and an image density measuring means that measures the image density of the developer image. A developing device control device for controlling the operation of the developing device based on the image density,
Control for forming a developer image for measurement in the developing device at a predetermined timing;
Control for the image density measuring means to measure the image density of the developer image for measurement;
The image density is compared with a reference image density that is an image density of a developer image for measurement having an acceptable quality formed under a predetermined image generation condition, and as a result of the comparison, the image density is the reference image density. If it is below, control to execute the forced consumption operation of the developer,
In the formation of the measurement developer image by the developing device, the control device for the development device forms the measurement developer image under image generation conditions in the formation of the reference developer image. A measuring unit for measuring a period required to form a predetermined amount of image;
A comparison is made as to whether or not a measurement period obtained by the measurement is equal to or less than a predetermined period, and as a result, if the measurement period is greater than the predetermined period, control is performed not to perform the forced consumption operation. A control device for a developing device according to 12 or 13. An image carrier;
A developing device for forming a developer image for transfer on the image carrier;
Image density measuring means for measuring the density of the developer image;
An image forming apparatus comprising: the developing device control device according to claim 12. An image carrier;
A developing device for forming a developer image for transfer on the image carrier;
An image forming apparatus comprising: the developing device control device according to claim 13.   The method for controlling a developing device according to claim 1, the step of forming a developer image for measurement at a predetermined timing, the step of measuring the image density of the developer image for measurement, and the image density. A step of comparing with a reference image density, which is an image density of a reference developer image having acceptable quality, formed under the image generation conditions, and if the comparison result shows that the image density is less than or equal to the reference image density A program for causing a computer to execute a step of executing the forced consumption operation of the developer.   A recording medium on which the program according to claim 17 is recorded, wherein the recording medium can be processed by a computer.

Images