JP4943131B2 - Developing device, image forming apparatus, toner supply method, program, and recording medium - Google Patents

Description

  The present invention relates to a developing apparatus, an image forming apparatus, a toner replenishing method, a program, and a recording medium that are provided in an image forming apparatus such as a copying machine, a printer, or a facsimile machine and that use a two-component developer as a developer.

  2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus that performs printing using toner as a developer, such as a copying machine, a printer, or a facsimile, is known. In this type of image forming apparatus, as described in Patent Document 1, for example, a photosensitive member is charged by a charger, and an electrostatic latent image corresponding to a print image is formed on the photosensitive member. The image is developed with toner by a developing device to form a toner image. Thereafter, the toner image is transferred from the photoreceptor onto the paper, and the toner image on the paper is fixed on the paper by a fixing device.

  When the image forming apparatus uses a two-component developer, the above-described developing device contains a two-component developer composed of toner and a carrier in a developing tank. When the toner in the developing tank is consumed by the developing operation, the toner is supplied to the developing tank from a toner supply device such as a toner hopper. In this case, the toner concentration in the developing tank is monitored by a toner concentration sensor including a magnetic permeability sensor provided in the developing tank, and when the toner concentration is reduced from the specified concentration, the toner hopper The toner supply operation is controlled.

  In the developing tank, there is provided a stirring member for stirring the developer, for example, a stirring screw or a stirring roller. When the developer in the developing tank is stirred by the stirring member, the charge amount is increased. On the other hand, if the developer is left without stirring, the charge amount is decreased by discharge.

  Here, the stirring member of the developing tank starts rotating when the printing operation by the image forming apparatus is started, and stirs the developer. Thereby, as shown in FIG. 6, the charge amount of the toner in the developing tank is small at the beginning of the printing operation, increases as the number of printed sheets increases by continuous printing, and becomes stable when the number of printed sheets reaches a predetermined number. For this reason, the detection of the toner concentration in the developing tank by the toner concentration sensor cannot accurately detect the toner concentration until the number of continuously printed sheets reaches a predetermined number.

  Therefore, in the conventional developing device, the toner supply from the toner hopper to the developing tank is performed in the first toner replenishing mode before the toner charge amount in the developing tank is stabilized, and after the toner charge amount in the developing tank is stabilized. Switches the toner supply mode as in the second toner supply mode. In the first toner supply mode, for example, a toner consumption amount is calculated from an image to be printed, and an amount of toner that supplements the toner consumption amount is supplied. In the second toner replenishment mode, toner is replenished so that the toner density in the developing tank detected by the toner density sensor becomes an appropriate density.

  For example, in Patent Document 1, in a configuration in which a two-component developer is used, a first toner supply mode in which toner is supplied based on the video count obtained by integrating the output levels of the pixels of the pixel image signal. And a second toner supply mode for supplying toner based on the toner concentration detected by the magnetic permeability sensor. The first toner replenishment mode is used at the start of the copying operation, and when the apparent magnetic permeability of the two-component developer is stabilized, the toner replenishment is switched to the second toner replenishment mode.

On the other hand, in Patent Document 2, in a configuration using a two-component developer, the amount of toner replenishment obtained from the detection value of the toner density sensor is set to the size of the image forming area that affects the toner consumption, Corrections are made based on toner reduction conditions using parameters such as the humidity in the apparatus, the number of times the photosensitive drum is driven, and the number of transfers.
JP 5-27596 (published on February 5, 1993) JP-A-8-146751 (released on June 7, 1996)

  In the configuration described in Patent Document 1, a toner consumption amount is calculated from a printed image, and a first toner replenishment mode for replenishing an amount of toner that supplements the toner consumption amount, and a developing tank detected by a toner density sensor The second toner supply mode in which toner is supplied is switched based on the toner density. Basically, if the toner density sensor can stably detect the toner density in the developing tank, toner supply is controlled only by the second toner supply mode.

  The switching from the first toner supply mode to the second toner supply mode can be performed, for example, depending on whether or not the number of continuous prints exceeds a specified number. That is, since the agitating member is driven to rotate in accordance with the printing operation, if the continuous printing number exceeds the specified number, the developer is sufficiently agitated by the rotation of the agitating member during the continuous printing period exceeding the specified number, and the toner It can be considered that the amount of charge of reached the stable range. Therefore, toner supply in the first toner supply mode is performed until the continuous print number exceeds the specified number, and toner supply in the second toner supply mode is performed after the continuous print number exceeds the specified number. That's fine.

  However, if a job in which the number of continuously printed sheets is 10 or less continues, toner replenishment in the first toner replenishment mode, that is, toner replenishment based on the predicted value of toner consumption is performed during the period during which these jobs are performed. The toner supply in the second toner supply mode, that is, toner supply based on the actual measurement value of the toner density sensor is not performed. For this reason, there is a problem that the deviation of the actual toner density in the developing tank with respect to the target toner density in the developing tank may increase.

  Therefore, according to the present invention, a developing device, an image forming apparatus, a toner replenishing method, a program, and a recording medium that can always maintain a proper toner density in a developing tank (developing device) and thereby obtain a good print image. The purpose is to provide.

  In order to solve the above problems, a developing device of the present invention uses a two-component developer containing toner and a carrier, has a stirring member for stirring the developer, and is formed on a latent image carrier. When an image is printed, a developer that develops an electrostatic latent image with the toner, a toner replenisher that replenishes the developer, a toner concentration sensor that detects the toner concentration of the developer in the developer, and A toner consumption amount calculating means for calculating a toner consumption amount associated with the developing operation from the image, an integrated toner consumption amount calculating means for integrating the toner consumption amount to obtain an integrated toner consumption amount, and a first toner supply mode. And a toner concentration control means for controlling a toner replenishment operation by the toner replenisher based on the accumulated toner consumption amount, wherein the first toner replenishment mode is provided. A determination unit configured to determine whether toner density adjustment processing is necessary based on a continuous execution amount; and the toner concentration control unit is configured to determine whether the toner density adjustment processing is necessary by the determination unit. In the toner density adjustment process, the toner supply operation of the toner replenisher is controlled based on the toner density detected by the toner density sensor after the stirring member is operated during non-development when the development operation is not performed. It is characterized by.

  The toner replenishing method of the present invention uses a two-component developer containing toner and carrier, has a stirring member for stirring the developer, and converts the electrostatic latent image formed on the latent image carrier into the toner. The toner replenishment operation for the developing device to be developed by the first toner replenishment mode is obtained by calculating the toner consumption amount accompanying the development operation when the image is printed from the image and integrating the toner consumption amount. In the toner replenishing method controlled based on the accumulated toner consumption amount, it is determined whether or not a toner density adjustment process is necessary based on a continuous execution amount of the first toner replenishment mode, and the toner density adjustment is determined in the determination. When it is determined that processing is necessary, as the toner concentration adjustment processing, after the stirring member is operated during non-development in which development operation is not performed, the toner concentration sensor is processed. It is characterized by controlling the toner supply operation based on the detection toner concentration over.

  According to the above configuration, in the first toner replenishment mode, a toner consumption amount accompanying a developing operation when an image is printed is calculated from the image, and the toner consumption amount is integrated to obtain an integrated toner consumption amount. The toner supply operation for the developing device is controlled based on the accumulated toner consumption. Further, based on the continuous execution amount of the first toner replenishment mode, it is determined whether or not the toner density adjustment process is necessary. If it is determined that the toner density adjustment process is necessary in this determination, the toner density adjustment process is performed. As described above, the toner replenishing operation to the developing device is controlled based on the toner density detected by the toner density sensor after the stirring member is operated at the time of non-development in which the developing operation is not performed.

  Here, in the first toner replenishment mode, for example, when the accumulated toner consumption amount reaches a predetermined amount, the toner is replenished so as to compensate for the predetermined amount of accumulated toner consumption amount. The continuous execution amount of the first toner replenishment mode is, for example, the number of executions and the execution time when the first toner replenishment mode is continuously performed. Specifically, for example, the number of developed images (Number of printed sheets). In the toner density adjustment process, the toner replenishing operation to the developing device based on the toner density detected by the toner density sensor is controlled so that the toner density in the developing device becomes an appropriate value.

  As described above, according to the configuration in which the toner density adjustment process is performed, the first toner supply mode is continuously performed, that is, the toner supply operation based on the prediction of the toner consumption amount is continuously performed. Further, it is possible to prevent a situation in which the toner density in the developing device is greatly deviated from an appropriate value (target value). As a result, the toner density in the developing device can always be maintained in an appropriate state, and a good printed image can be obtained.

  The developing device includes detection means for detecting a switching timing from the first toner replenishment mode to the second toner replenishment mode, and the toner density control means detects the switching timing when the switching timing is detected. As a second toner supply mode, a toner supply operation by the toner supply device may be controlled based on a toner density detected by the toner density sensor.

  According to the above configuration, the detection unit detects the switching timing between the first toner supply mode and the second toner supply mode, and the toner density control unit detects the switching timing by the detection unit. In the second toner supply mode, the toner supply operation by the toner supply device is controlled based on the toner concentration detected by the toner concentration sensor.

  Here, when the developer is sufficiently stirred, the charge amount is stabilized, and when the developer is not sufficiently stirred, the charge amount is unstable. When the charge amount is unstable, toner density control based on the detection result of the toner density sensor is inaccurate. Accordingly, the switching timing between the first toner supply mode and the second toner supply mode is a timing at which the charge amount of the developer in the developing device is stabilized, for example, stirring of the developing device driven in accordance with the developing operation. The continuous drive time of the member is set to a timing when the predetermined time is reached.

  In the developing device, the toner concentration control unit supplies the toner with an amount that supplements the accumulated toner consumption when the accumulated toner consumption reaches a predetermined value in the first toner replenishment mode. The toner consumption amount by the integrated toner consumption calculating means when the toner concentration detected by the toner concentration sensor is higher than an appropriate value in the toner concentration adjustment process. It is good also as a structure made to correct in the direction which decreases.

  According to the above configuration, in the toner density adjustment process, when the toner density detected by the toner density sensor is higher than an appropriate value, the value of the cumulative toner consumption amount by the cumulative toner consumption amount calculation unit is corrected to decrease. Therefore, when the first toner replenishment mode is performed after the toner density adjustment processing is performed, the integrated toner consumption amount does not easily reach a predetermined value for toner replenishment from the toner replenisher to the developing device. As a result, the toner density in the developing device is easily corrected in a direction approaching the appropriate value from a state higher than the appropriate value. The correction is preferably performed by subtracting a toner amount corresponding to an amount exceeding the appropriate value of the toner density from the detected toner density detected by the toner density sensor.

  In the developing device, the detection unit may detect the switching timing from the first toner supply mode to the second toner supply mode based on whether or not the number of continuously developed images has reached a predetermined number. Good.

  According to the above configuration, the detection means determines whether or not the continuous development number of the image has reached a predetermined number, for example, the continuous development number (continuous development number) (continuous). The number of prints is detected based on whether or not the number has reached 11. Therefore, the switching timing can be accurately and easily performed.

  Whether the development is continuous or not can be determined by determining whether the time from one development to the next development is within a predetermined time. For example, when developing a plurality of images in one job, since the development is performed one after another at short time intervals, it can be regarded as continuous development.

  In the developing device, the determination unit may perform the determination operation with the execution amount of the first toner supply mode continued as the number of developed images.

  According to the above configuration, the determination unit determines whether the continuous execution amount of the first toner replenishment mode is a toner density adjustment process based on whether the number of developed images, for example, the number of developed images (printed number) is 200 or more. Whether or not is necessary. Therefore, it is possible to accurately and easily determine whether or not toner density adjustment processing is necessary.

  As described above, according to the configuration for performing the toner density adjustment process of the present invention, the first toner supply mode is continuously performed, that is, the toner supply operation based on the prediction of the toner consumption is continuously performed. For this reason, it is possible to prevent a situation in which the toner density in the developing device deviates greatly from an appropriate value (target value). As a result, the toner density in the developing device can always be maintained in an appropriate state, and a good printed image can be obtained.

  FIG. 2 is a schematic longitudinal sectional view of the multifunction machine 1 including the image forming apparatus according to the present embodiment. The multifunction device 1 includes a document feeder (hereinafter referred to as SPF: Single Pass Feeder) 2 and an image forming apparatus 3.

  The image forming apparatus 3 forms a monochrome image on a recording sheet (sheet) in accordance with image data obtained by scanning a document conveyed by the SPF 2 or image data input from the outside. The image forming apparatus 3 includes a scanner unit (document reading device) 11, a printer unit 12, and a paper feed unit 13.

  The printer unit 12 includes an optical writing unit 21, a developing unit (developing device, developing device) 22, a toner hopper (toner replenishing device, developing device) 31, a toner supply container 32, a photosensitive member (latent image carrier) 23, a charging unit. A container 24, a cleaner unit 25, a transfer unit 26, a fixing unit 27, a paper transport path 28, a paper discharge tray 29, and a manual feed tray 30. The paper feed unit 13 includes a paper feed cassette 41 and a large capacity paper feed (LCC) 42. These paper feed cassette 41 and large-capacity paper feed cassette 42 contain recording paper used for image formation.

  The scanner unit 11 includes a document placing table 51 made of glass on the upper surface, and a light source holder 52, a mirror group 53, and a CCD (imaging device) 54 below the document placing table 51. In the scanner unit 11, when scanning a document sent from the SPF 2, the light source holder 52 and the mirror group 53 are stopped at a position on one end side of the document placing table 51. In this case, when the document is conveyed from the SPF 1, light is emitted from the light source of the light source holder 52 to the document, and reflected light from the document is imaged on the CCD 54 via the mirror group 53, and an electronic image is obtained by the CCD 54. Converted to data. In order to perform such an operation, a reading window is formed at one end of the upper surface of the scanner unit 11.

  In the printer unit 12, the charger 24 uniformly charges the surface of the photoconductor 23 to a predetermined potential. Although the image forming apparatus 3 uses the charger type charger 24, a contact type roller type or brush type charger can also be used.

  The optical writing unit 21 adopts a two-beam system including two laser irradiation units 61a and 61b in order to cope with high-speed printing processing, and the burden associated with increasing the irradiation timing is reduced. The optical writing unit 21 irradiates laser light from the laser irradiation units 61a and 61b in accordance with input image data. The laser light is irradiated to the uniformly charged photosensitive member 23 through the mirror groups 62a and 62b to expose the photosensitive member 23. As a result, an electrostatic latent image corresponding to the image data is formed on the surface of the photoreceptor 23.

  The developing unit 22 is disposed to face the photoconductor 23 and visualizes the electrostatic latent image formed on the surface of the photoconductor 23 with black toner. The cleaner unit 25 removes and collects toner remaining on the surface of the photoconductor 23 after development and image transfer.

  The transfer unit 26 transfers the toner image formed on the surface of the photoreceptor 23 onto the recording paper by applying an electric field having a polarity opposite to that of the electric charge of the electrostatic latent image. For example, when the electrostatic latent image has a charge of (−) polarity, an electric field of (+) polarity is applied. The transfer unit 26 includes a transfer belt (conveyance belt) 71, a driving roller 72, a driven roller 73, and a transfer roller 74. The transfer roller 74 is provided at a contact portion between the photoconductor 23 and the transfer belt 71 and applies a transfer electric field.

  The transfer roller 74 generates the electric field for transferring the toner image on the photoreceptor 23 onto the recording paper. The transfer roller 74 is composed of a conductive roller that is elastically supported. Since the transfer roller 74 has elasticity, the photosensitive member 23 and the transfer belt 71 can be brought into surface contact having a predetermined width (transfer nip) instead of line contact, and the transfer efficiency of the toner image onto the paper is improved. is doing.

  The transfer unit 26 further includes a static elimination roller 75, a cleaning unit 76, a static elimination mechanism 77, and a tension roller 78. The neutralization roller 75 is provided on the downstream side of the transfer area in order to remove the electric charge applied by the electric field in the transfer area from the recording paper. Thereby, the conveyance of the paper to the next process can be performed smoothly. The cleaning unit 76 removes toner stains on the transfer belt 71, and the charge removal mechanism 77 discharges the transfer belt 71. The static elimination mechanism 77 may be either one that performs static elimination by grounding or one that positively applies an electric field having a polarity opposite to the polarity of the transfer electric field. The tension roller 78 applies tension to the transfer belt 71.

  The fixing unit 27 heats and melts the toner image transferred onto the recording paper and fixes it on the recording paper. The fixing unit 27 includes a heating roller 81 and a pressure roller 82. The heating roller 81 has a built-in heat source, and the pressure roller 82 is pressed against the heating roller 81 with a predetermined pressure.

  A recording sheet on which an image is printed is discharged to the discharge tray 29. Instead of the paper discharge tray 29, a post-processing device for paper discharge (staple, punching, etc.) or a multi-stage paper discharge tray can be arranged as an option.

  The paper feed cassette 41 and the large-capacity paper feed cassette 42 are for storing recording paper (sheets) used for image formation. For high-speed printing processing, the paper feed cassette 41 disposed below the printer unit 12 can store 500 to 1500 sheets of standard size recording paper. On the other hand, the large-capacity paper feed cassette 42 arranged outside the housing of the image forming apparatus 3 can store a large amount of a plurality of types of recording paper. The manual feed tray 30 is for feeding recording paper of an irregular size.

  FIG. 3 is a schematic diagram showing a configuration around the photoconductor 23 in the multifunction machine 1 shown in FIG. As shown in FIG. 23, the developing unit 22 includes a toner concentration sensor 92 including a magnetic permeability sensor in a developing tank 91, and a developing roller 93 and a stirring roller (stirring member) 94 inside the developing tank 91. In addition, a two-component developer (not shown) composed of toner and carrier is accommodated in the developing tank 91.

  The developing roller 93 supplies the toner in the developing tank 91 to the electrostatic latent image formed on the photoconductor 23 and develops the electrostatic latent image. The agitating roller 94 agitates the developer in order to make the toner density uniform in the developing tank 91 and to charge the developer.

  The toner hopper 31 includes a stirring roller 95 and a toner replenishing screw 96. The toner agitating roller 95 agitates the toner in the toner hopper 31, and the toner replenishing screw 96 replenishes the toner in the toner hopper 31 to the developing unit 22 by a rotating operation. The toner replenishment screw 96 can accurately control the toner replenishment amount by controlling the rotation amount (rotation time).

  In addition, toner is supplied to the toner hopper 31 from the toner supply container 32 shown in FIG. The toner supply container 32 is, for example, a cartridge type, has a cylindrical bottle shape, and supplies toner inside the toner hopper 31 while rotating.

  In the configuration of FIG. 3, the photoconductor 23 is charged to a predetermined potential by a charger 24, and this photoconductor 23 is irradiated with laser light from the optical writing unit 21 according to an image read by the scanner unit 11, for example. An electrostatic latent image corresponding to the read image (original image) is formed. The electrostatic latent image is developed with toner supplied from the developing roller 93 of the developing unit 22 and becomes a toner image. This toner image is transferred by a transfer roller 74 onto a recording sheet conveyed between the transfer belt 71 and the photoreceptor 23. The toner image transferred to the recording paper is then sent to the fixing unit 27 where the toner image is fixed on the recording paper and then discharged from the multifunction device 1.

  In the toner hopper 31, the toner supply to the developing unit 22 is performed by rotating the toner supply screw 96. The toner replenished from the toner hopper 31 to the developing unit 22 is agitated by the agitating roller 94 in the developing tank 91 and mixed with the carrier, and this agitation increases the charge amount.

  FIG. 1 is a block diagram illustrating a configuration for controlling toner replenishment from the toner hopper 31 to the developing unit 22 provided in the multifunction machine 1 according to the present embodiment. As shown in FIG. 1, the multi-function device 1 includes an image processing unit 110, a pixel count unit (toner consumption calculation unit) 120, a toner consumption calculation unit (toner consumption calculation unit) 130, a toner density sensor 92, a toner density. A control unit (toner density control means) 140, a toner hopper 31 and a developing unit 22 are provided.

  The image processing unit 110 has a conventionally well-known configuration. For example, the image processing unit 110 performs predetermined image processing on an image signal of an original image read by the scanner unit 11 and outputs the image signal to the optical writing unit 21.

  FIG. 4 is a block diagram showing a configuration of the pixel count unit 120. As shown in FIG. 4, the pixel counting unit 120 includes a counting unit 121, a weighting calculation unit 122, a weighting counting table 123, and an integration unit 124.

  The counting unit 121 counts the gradation of the input multi-valued image (for example, a multi-gradation image such as 16 gradations or 256 gradations) for each pixel. For example, in the case of a 16-gradation multi-gradation image in which the signal value of each pixel takes any value from 0 to 15, the counting unit 121 determines whether the gradation is 0 to 15 for each pixel. Count.

  The weighting calculation unit 122 weights the gradation value counted for each pixel by the counting unit 121 for each pixel. Specifically, for each pixel, the weighting calculation unit 122 acquires a weighting coefficient corresponding to the gradation value from the weighting coefficient table 123 and multiplies the acquired weighting coefficient by the gradation value to obtain a pixel count value. Ask. This pixel count value is an index indicating the toner consumption amount for each pixel. The weighting coefficient table 123 shows the correspondence between gradation values and weighting coefficients. In this way, the pixel count unit 120 obtains a pixel count value for each pixel by the count unit 121, the weighting calculation unit 122, and the weighting coefficient table 123.

  The accumulation unit 124 performs accumulation over all pixels of the pixel count value obtained for each pixel. That is, the integrating unit 124 integrates the pixel count value obtained by multiplying the gradation value by the weighting coefficient by the weighting calculating unit 122 for all the pixels of the input multi-valued image, and calculates the total pixel count value. In this case, the integrating unit 124 calculates and obtains the pixel count value of one image.

  The toner consumption amount calculation unit 130 calculates the toner consumption amount when printing one image from the integrated value of the pixel count value (gradation data count value) obtained by the pixel count unit 120.

  The toner density control unit 140 uses the toner consumption obtained from the toner consumption calculation unit 130, the toner density detected by the toner density sensor 92, and the toner from the toner hopper 31 to the developing unit 22 based on the accumulated number of printed sheets. Control replenishment.

  That is, the toner density control unit 140 calculates the toner consumption amount calculation unit 130 when the number of continuous prints in the multifunction device 1 (the number of images to be continuously developed in the development unit 22) is less than a predetermined number. Toner supply control based on the toner consumption amount (first toner supply mode) is performed. That is, in the first toner replenishment mode, the toner concentration control unit 140 determines that the toner consumption amount calculated by the toner consumption amount calculation unit 130 (hereinafter referred to as “calculated toner consumption amount”) is the toner replenishment screw of the toner hopper 31. Each time the amount of toner replenishment due to rotation at 96 is reached, the toner replenishment screw 96 is rotated for 1 second.

  In addition, the toner density control unit 140 uses the toner density sensor 92 when the number of continuous prints (the number of images continuously developed by the developing unit 22) in the multifunction machine 1 is equal to or greater than a predetermined number (for example, 11). Toner supply control (second toner supply mode) is performed based on the detected toner density.

  In the second toner replenishment mode, the toner density detection by the toner density sensor 92 is performed 15 times in 0.5 seconds, and the average value thereof is determined as the toner density in the developing tank 91. This toner density determination operation is continuously performed during a printing operation (development operation) at a rate of twice per second.

  Further, the toner density control unit 140 continuously performs a print job in which the number of continuous prints is less than a predetermined number (for example, 11 sheets), and as a result, the accumulated number of prints becomes a predetermined number (for example, 200 sheets) or more. In accordance with the detection result of the toner density sensor 92, toner replenishment control (toner density adjustment processing) from the toner hopper 31 to the developing tank 91 is performed.

  FIG. 5 is a table showing the relationship between the number of continuously printed sheets and the charge amount of toner in the multifunction machine 1, and FIG. 6 is a graph showing the relationship. As can be seen from FIGS. 5 and 6, when the number of continuously printed sheets reaches 11, the charge amount of the toner is almost stable. Therefore, when the number of continuously printed sheets reaches 11 and the developer is appropriately stirred in the developing tank 91, it is considered that the detection of the toner density by the toner density sensor 92 is usually almost stable. Therefore, in the present embodiment, the predetermined number is 11 (printing 11 original images). In continuous printing, a case where the time from the end of one printing to the start of the next printing is within 3 seconds is regarded as continuous printing.

  In the image forming apparatus 3 of the present embodiment, the appropriate value of the toner concentration in the developing tank 91 detected by the toner concentration sensor 92 is 6%. As an example, the output voltage of the toner concentration sensor 92 when the detected toner concentration is 6% is 2.5V. Therefore, the toner density control unit 140 starts toner supply when the output voltage of the toner density sensor 92 is higher than 2.5V, and supplies toner when the output voltage is lower than 2.5V. Stop. Further, the output voltage of the toner density sensor 92 is changed by changing the control voltage of the toner density sensor 92. Therefore, the control voltage of the toner density sensor 92 is set so that the output voltage of the toner density sensor 92 when the detected toner density is 6% is 2.5V. In order to perform such adjustment, the multi-function device 1 includes a temperature sensor (not shown) and a humidity sensor (not shown). The deviation in the output voltage of the toner concentration sensor 92 due to the environmental change as described above also occurs when the carrier of the developer changes with time. In such a case, the control voltage of the toner concentration sensor 92 is adjusted. Is called. Note that the toner density control unit 140 may adjust the control voltage of the toner density sensor 92.

  FIG. 7 is a block diagram showing a configuration of the toner density control unit 140 shown in FIG. As shown in FIG. 7, the toner concentration control unit 140 performs a toner replenishment control unit (toner toner) in order to perform toner replenishment control and toner concentration adjustment processing in the first toner replenishment mode and the second toner replenishment mode described above. Density control means, determination means, detection means, integrated toner consumption calculation means) 141, toner consumption counter (integrated toner consumption calculation means) 142, printed sheet counter (detection means) 143, toner hopper control section (toner density control) Means) 144 and a developing unit control section (toner density control means) 145.

  The toner consumption amount counter 142 integrates the toner consumption amount obtained from the toner consumption amount calculation unit 130. The printed sheet counter 143 accumulates the number of sheets printed on the image forming apparatus 3 (the number of images developed by the developing unit 22). The toner replenishment determination unit 141 determines whether to perform the first toner replenishment mode or the second toner replenishment mode depending on whether or not the number of continuous prints in the image forming apparatus 3 has reached a predetermined number. To do. Further, after the end of continuous printing, it is determined whether or not to perform toner density adjustment processing based on the cumulative number of printed sheets. Specifically, when the cumulative number of printed sheets is 200 or more, it is determined that the toner density adjustment processing is necessary. On the other hand, when the cumulative number of printed sheets is less than 200, it is determined that the toner density adjustment processing is unnecessary. In each of these modes and processes, it is determined whether or not a toner replenishing operation from the toner hopper 31 to the developing unit 22 is performed.

  The reason why the threshold value of the cumulative number of printed sheets is set to 200 is as follows. For example, when printing on A4 size paper with solid black, the toner density (T / D) based on the pixel count and the toner density (T / D) detected by the toner density sensor (magnetic permeability sensor) 92 The maximum error becomes about ± 1.5% (the toner amount is about 800 mg) after printing about 200 sheets. This is because it is preferable to determine whether or not toner replenishment is necessary within such an error range in order to maintain a good toner density.

  Here, in the present embodiment, the relationship between the toner replenishment amount in the first and second toner replenishment modes and the integrated value of the toner consumption amount counter 142, and the toner detected by the toner concentration sensor 92 in the toner concentration adjustment processing The relationship between the density and the correction value of the toner consumption counter 142 will be described.

  In the present embodiment, in the first and second toner supply modes, the toner supply screw 96 of the toner hopper 31 is rotated for 1 second to supply toner from the toner hopper 31 to the developing tank 91. The amount of toner to be replenished by rotating the toner replenishing screw 96 for 1 second is 450 mg. This toner amount corresponds to 191,650,000 when converted to a pixel count value in the pixel count unit 120.

  When the toner density (T / D) is an appropriate value (6%), the toner amount in the developing tank 91 is 900 g, and the initial toner density (T / D) is set to 6%. The toner consumption counter 142 is set to zero. Therefore, as shown in FIG. 8, the toner consumption counter 142 accumulates the toner consumption simultaneously with the start of printing, and when the count value reaches −191,650,000, the toner supply screw 96 With the rotation for 1 second, 450 mg of toner is supplied, and the toner consumption counter 142 is reset to zero.

  Further, in the toner density adjustment process, when the first toner supply mode is continuously performed and the count value of the print sheet counter 143 reaches 200, the toner density adjustment based on the toner density detected by the toner density sensor 92 is performed. Take control.

  For example, when the toner density (T / D) detected by the toner density sensor 92 is 5.95%, 0.05% which is a difference from the appropriate value of the toner density of 6.00% is 450 mg in terms of the toner amount. It corresponds to. Therefore, the toner supply of 450 mg (corresponding to the rotation amount of the toner supply screw 96 for 1 second) is performed to set the toner concentration to 6%, and the toner consumption counter 142 is reset to 0.

Further, when the toner density (T / D) detected by the toner density sensor 92 is 6.02% (> 6.00%), it is 0.02% which is a difference from the appropriate value of the toner density of 6.00%. Corresponds to 180 mg in terms of toner amount. A toner amount of 180 mg corresponds to 7,666,000 when converted to a count value of the toner consumption counter 142. Therefore, the count value of the toner consumption counter 142 is corrected to 7,666,000. This process is to correct the accumulated toner consumption value so as to decrease.

  In the above configuration, the toner replenishing operation in the image forming apparatus 3 will be described below based on the flowchart of FIG.

  When printing is instructed in the multifunction device 1 (S1), for example, a printing operation for a document image read by the scanner unit 11 is started (S2). In the period from the start of the printing operation in S2 to the end of the printing operation in S13, the stirring roller 94 of the developing unit 22 is rotationally driven by the control of the developing unit control unit 145.

  The pixel count unit 120 calculates the pixel count value of the document image to be printed (S3), and the toner consumption amount calculation unit 130 calculates the toner consumption amount from the pixel count value calculated by the pixel count unit 120 (S4). This toner consumption is, for example, for one image. Further, the toner replenishment determination unit 141 of the toner density control unit 140 detects the number of continuous prints (S5). Here, the number of printed originals actually processed is detected. Note that the continuous print number corresponds to, for example, the number of prints performed in one job.

  Next, the toner consumption amount counter 142 of the toner density control unit 140 determines that the number of processed continuous prints is less than 11 (S6), and prints one original image obtained from the toner consumption amount calculation unit 130. Are accumulated (S7). Further, the print number counter 143 of the toner density control unit 140 accumulates the number of prints (S8).

  Next, the toner replenishment determination unit 141 determines whether or not the toner consumption amount accumulated by the toner consumption amount counter 142 has reached the toner replenishment amount due to the rotation of the toner replenishment screw 96 of the toner hopper 31 for one second. (S9).

  If the determination result in S9 is NO, the process returns to S3. If YES, the toner hopper control unit 144 of the toner density control unit 140 rotates the toner replenishing screw 96 of the toner hopper 31 for one second. (S10). In addition, the toner replenishment determining unit 141 resets the toner consumption counter 142 to 0 (S11).

  Thereafter, the toner replenishment determination unit 141 determines whether or not printing of the continuous print number has been completed (S12). If the result of this determination is that printing of the continuous print number has not been completed, the process returns to S1, while if printing of the continuous print number has been completed, printing is ended (S13), and then toner density adjustment processing is performed ( S14). Note that whether or not the printing of the continuous print number has been completed is determined based on whether or not the time from the end of one printing to the start of the next printing is within 3 seconds as described above.

  In the determination of S6, if the number of processed continuous printed sheets is 11 or more, the toner replenishment determination unit 141 validates the toner density detected by the toner density sensor 92 (S15), and based on the detected toner density. It is then determined whether or not toner replenishment from the toner hopper 31 is necessary (S16).

  If the result of this determination is that toner replenishment is necessary, the toner hopper controller 144 rotates the toner replenishment screw 96 of the toner hopper 31 for only one second (S17). Thereafter, the toner replenishment determination unit 141 resets the print number counter 143 to 0 (S18), and proceeds to S11. If the result of determination in S16 is that toner supply is not necessary, the toner supply determination unit 141 resets the print number counter 143 to 0 (S18), and proceeds to S11.

  Next, the toner density adjustment processing in S14 will be described with reference to FIG. FIG. 10 is a flowchart showing the toner density adjustment processing in S14.

  In the toner density adjustment process, the toner replenishment determining unit 141 determines whether or not the cumulative number of printed sheets accumulated by the printed number counter 143 is 200 or more (S31). As a result of this determination, if the cumulative number of printed sheets is less than 200, the process is terminated. If the cumulative number of printed sheets is 200 or more, the developing unit controller 145 of the toner density controller 140 causes the developing unit 22 to agitate. The roller 95 is rotated for 5 seconds (S32). The rotation of the stirring roller 95 for 5 seconds corresponds to the rotation amount of the stirring roller 95 when 11 sheets are continuously printed, and can stabilize the charge amount of the developer in the developing tank 91.

  Thereafter, the toner replenishment determination unit 141 determines whether or not the detected toner density of the toner density sensor 92 is 6% as an appropriate value (S34). If the detected toner density is 6%, the print number counter 143 is set to 0. (S35) and the process is terminated.

  On the other hand, if the detected toner density is less than 6% (S36), the toner hopper controller 144 rotates the toner replenishing screw 96 of the toner hopper 31 and the toner in the developing tank 91 detected by the toner density sensor 92 is detected. The toner is supplied to the developing tank 91 until the density reaches 6% (S37). Thereafter, the toner replenishment determination unit 141 resets the print number counter 143 to 0 (S35) and ends the process.

  If the detected toner density exceeds 6%, the toner replenishment determination unit 141 corrects the count value of the toner consumption counter 142 (S38), and then resets the print number counter 143 to 0 (S35). The process ends.

  The process of S38 is for suppressing toner supply based on the count value of the toner consumption counter 142 in the first toner supply mode because the detected toner density exceeds 6%. Here, for example, a process of reducing the toner consumption corresponding to the toner density exceeding 6% with respect to the count value of the toner consumption counter 142 is performed. Therefore, the value of the cumulative toner consumption is corrected so as to decrease.

  As described above, in the multi-function device 1 according to the present embodiment, when the toner replenishment in the first toner replenishment mode is continuously performed for a long period of time, the total number of printed sheets reaches a predetermined number (for example, 200). Then, after the developer in the developing tank 91 is agitated to stabilize the charge amount, the toner density in the developing tank 91 is adjusted to an appropriate value based on the toner density detected by the toner density sensor 92. That is, when the toner supply control based on the calculated value of the toner consumption is continuously performed for a predetermined period (over a predetermined number of printed sheets), the toner density based on the detection result of the actual toner density by the toner density sensor 92 Control is performed. Therefore, the toner concentration in the developing tank 91 can always be maintained in an appropriate state regardless of the number of continuous prints, that is, even when the first toner supply mode is continuously performed for a long period of time. As a result, the multifunction device 1 can obtain a good print image.

  In the above description, the multifunction device 1 is described as a monochrome type. However, the present invention is not limited to this, and can naturally be applied to a full-color type multifunction device (image forming apparatus). It is. In this case, toner replenishment control is control for each color toner replenishment, and the processing in the pixel count unit 120 shown in FIG. 4 is also performed for each color. The image processing unit 110 is an image process for a full-color image, and specifically includes an input signal processing unit, a region separation processing unit, a color correction / black generation processing unit, a zoom scaling processing unit, a spatial filter processing unit, and A conventionally known functional unit such as a halftone correction processing unit is provided.

  Finally, each block (the pixel count unit 120, the toner consumption calculation unit 130, and the toner density control unit 140) included in the multifunction machine 1 including the developing device of the present invention may be configured by hardware logic. Alternatively, it may be realized by software using a CPU as follows.

  That is, the MFP 1 includes a central processing unit (CPU) that executes instructions of a control program that realizes each function, a ROM (read only memory) that stores the program, a RAM (random access memory) that expands the program, A storage device (recording medium) such as a memory for storing the program and various data is provided. An object of the present invention is to provide a recording medium in which a program code (execution format program, intermediate code program, source program) of a control program of the multifunction machine 1 that is software that realizes the above-described functions is recorded so as to be readable by a computer. This can also be achieved by supplying the MFP 1 and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU).

  Examples of the recording medium include a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, and an optical disk such as a CD-ROM / MO / MD / DVD / CD-R. Card system such as IC card, IC card (including memory card) / optical card, or semiconductor memory system such as mask ROM / EPROM / EEPROM / flash ROM.

  Further, the multifunction device 1 may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication. A net or the like is available. Also, the transmission medium constituting the communication network is not particularly limited. For example, even in the case of wired such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL line, etc., infrared rays such as IrDA and remote control, Bluetooth ( (Registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, and the like can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  The configuration of the present invention can be applied to various electrophotographic printing apparatuses (image forming apparatuses) including a developing device that performs development with a two-component developer.

FIG. 2 is a block diagram illustrating a configuration of a multifunction peripheral according to an embodiment of the present invention, and illustrating a configuration for controlling toner supply from a toner hopper to a developing unit. 1 is a schematic longitudinal sectional view of a multi-function machine including a developing device according to an embodiment of the present invention. FIG. 3 is a schematic diagram illustrating a configuration around a photoconductor in the multifunction peripheral illustrated in FIG. 2. It is a block diagram which shows the structure of the pixel count part shown in FIG. FIG. 3 is an explanatory diagram showing a relationship between the number of continuously printed sheets and the charge amount of toner in the multifunction machine shown in FIG. 2. 3 is a graph showing the relationship between the number of continuously printed sheets and the charge amount of toner in the multifunction machine shown in FIG. 2. FIG. 2 is a block diagram illustrating a configuration of a toner density control unit illustrated in FIG. 1. The relationship between the toner replenishment amount in the first toner replenishment mode and the integrated value of the toner consumption amount counter shown in FIG. 7, and the toner concentration detected by the toner concentration sensor and the toner consumption amount shown in FIG. It is explanatory drawing which shows the relationship with the correction value of a counter. 6 is a flowchart illustrating a toner density control operation of the developing device according to the embodiment of the present invention. 10 is a flowchart showing toner density adjustment processing in S14 shown in FIG.

Explanation of symbols

1 MFP 22 Developer unit (Developer, Developer)
23 photoconductor (latent image carrier)
31 Toner hopper (toner replenisher, developing device)
91 Developing tank 92 Toner concentration sensor 93 Developing roller 94 Stirring roller (stirring member)
96 Toner Supply Screw 120 Pixel Count Unit (Toner Consumption Calculation Unit)
130 Toner consumption calculation unit (toner consumption calculation means)
140 Toner density controller (toner density controller)
141 Toner replenishment determination unit (toner density control means, determination means, detection means, integrated toner consumption amount calculation means)
142 Toner consumption counter (integrated toner consumption calculation means)
143 Printed sheet counter (detection means)
144 Toner hopper control unit (toner density control means)
145 Development unit controller (toner density control means)

Claims (6)

A developing device that uses a two- component developer containing toner and a carrier, has a stirring member for stirring the developer, and develops the electrostatic latent image formed on the latent image carrier with the toner;
A toner replenisher having a toner replenishment screw and rotating the toner replenishment screw to replenish toner to the developer;
A toner concentration sensor for detecting the toner concentration of the developer in the developing device;
A toner consumption amount calculating means for calculating a toner consumption amount associated with a developing operation when an image is printed from the image;
Integrated toner consumption calculating means for integrating the toner consumption to obtain an integrated toner consumption;
Detecting means for detecting the switching timing from the first toner replenishment control to the second toner replenishment control based on whether or not the processed continuous print number has reached a predetermined number ;
As the first toner replenishment control, the toner replenishing operation by the toner replenisher is controlled based on the accumulated toner consumption amount, and the second toner is detected when the detection unit detects the switching timing. As a replenishment control, in a developing device comprising a first toner concentration control means for controlling a toner replenishing operation by the toner replenisher based on a toner concentration detected by the toner concentration sensor,
Determination means for determining whether or not toner density adjustment processing is necessary based on the cumulative number of developed images after continuous printing ;
When the determination unit determines that the toner density adjustment process is necessary, the toner density sensor is operated as the toner density adjustment process after the agitating member is operated during non-development in which a developing operation is not performed. Second toner concentration control means for controlling the toner replenishing operation of the toner replenisher based on the detected toner concentration of
In the second toner replenishment control, the first toner concentration control means controls the toner replenisher so that the toner replenishment screw rotates for a predetermined time,
In the first toner replenishment control, when the accumulated toner consumption amount reaches a toner replenishment amount due to the rotation of the toner replenishment screw for the predetermined time, the toner replenishment screw rotates for the predetermined time. A developing device that controls the toner replenisher. In the first toner replenishment control, the first toner density control means supplies, from the toner replenisher, an amount of toner that supplements the accumulated toner consumption when the accumulated toner consumption reaches a predetermined value. In the toner density adjustment process, when the toner density detected by the toner density sensor is higher than an appropriate value, the value of the cumulative toner consumption by the cumulative toner consumption calculation means is decreased. The developing device according to claim 1, wherein the developing device is corrected in a direction. An image forming apparatus characterized by comprising a developing device according to claim 1 or 2. A developer that uses a two- component developer including a toner and a carrier, has a stirring member that stirs the developer, and develops the electrostatic latent image formed on the latent image carrier with the toner; and for toner replenishment A developing device having a screw, and a toner replenisher that rotates the toner replenishing screw to replenish toner to the developer, and a toner concentration sensor that detects the toner concentration of the developer in the developer In the toner replenishing method executed using
A toner consumption calculation step of calculating toner consumption associated with the developing operation when an image is printed from the image;
A detection step of detecting a switching timing from the first toner supply control to the second toner supply control based on whether or not the processed continuous print number has reached a predetermined number ;
An integrated toner consumption calculating step of integrating the toner consumption to obtain an integrated toner consumption;
As the first toner replenishment control, the toner replenishing operation by the toner replenisher is controlled based on the accumulated toner consumption amount, and the second toner is detected when the switching timing is detected in the detection step. As a replenishment control, a first toner concentration control step for controlling a toner replenishing operation by the toner replenisher based on a toner concentration detected by the toner concentration sensor;
A determination step of determining whether toner density adjustment processing is necessary based on the cumulative number of developed images after continuous printing ;
When it is determined in the determination step that the toner density adjustment process is necessary, the toner density adjustment process is performed after the agitating member is operated during non-development in which a developing operation is not performed. A second toner concentration control step for controlling a toner replenishing operation of the toner replenisher based on the detected toner concentration ,
In the second toner supply control in the first toner concentration control step , the toner supply device is controlled so that the toner supply screw rotates for a predetermined time,
In the first toner replenishment control, when the accumulated toner consumption amount reaches a toner replenishment amount due to the rotation of the toner replenishment screw for the predetermined time, the toner replenishment screw rotates for the predetermined time. A toner replenishing method comprising controlling the toner replenisher. Program for causing a computer to function as each means of the developing apparatus according to claim 1 or 2. A computer-readable recording medium on which the program according to claim 5 is recorded.

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