JP2007003922A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of finely controlling toner concentration in accordance with the interior environment state of the image forming apparatus. <P>SOLUTION: The image forming apparatus includes a control means 11 which extracts a correction value corresponding to the detection results detected by an exterior temperature/humidity detecting part 12 from a correction table wherein a correction value for correcting a control reference value for controlling the toner concentration to an appropriate control reference value on the basis of the exterior temperature/humidity is preliminarily set, and then, corrects the control reference value on the basis of the extracted correction value. The image forming apparatus also includes a state detecting means 13 for detecting the interior environment state of the image forming apparatus, and a plurality of kinds of correction tables are preliminarily set in accordance with the interior environment state of the image forming apparatus. In correcting the control reference value, the control means 11 selects the correction table corresponding to the detection results out of the plurality of kinds of correction tables on the basis of the detection results detected by the state detecting means 13, and also, the control means 11 extracts the correction value by using the selected correction table. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus including a developing device that develops an electrostatic latent image using a developer having toner in an image forming apparatus such as a copying machine, a printer, and a facsimile machine.

  In general, in an image forming apparatus such as a copying machine, a printer, or a facsimile, an image formed by an image forming unit is transferred to a recording sheet, and is usually formed on a photoreceptor using a developer having toner. A developing device for developing the electrostatic latent image is provided.

  In such an image forming apparatus, a two-component developer composed of a toner and a magnetic carrier has been widely used as a developer used in the developing device. In such a developing device, the mixing ratio (toner concentration) of toner and carrier is an important factor in terms of the developing effect. That is, when the toner density is less than the appropriate value, the image density is lowered, and when the toner density is more than the appropriate value, inconveniences such as so-called fogging occur. Accordingly, in order to maintain a stable image density, it is desirable to keep the toner density constant. However, the toner density is greatly affected by changes in the physical properties of the developer itself over time and changes in physical properties due to the state of the image forming apparatus itself, for example, the installation environment (temperature and humidity) and the usage environment such as the number of continuous sheets to be passed. .

Conventionally, in consideration of the above points, for example, the temperature inside or near the image forming apparatus is detected, and it is determined whether or not the detected temperature is equal to or lower than a predetermined set value. Then, depending on the result, there is one that selects whether to apply a low-temperature environment correction table or a normal correction table (see, for example, Patent Document 1).
JP 2003-91105 A

  However, in the device described in Patent Document 1 described above, since the determination is made based on the temperature inside or outside the apparatus, when the temperature inside the apparatus is used as a reference, for example, from the recording paper when the sheet is passed It cannot cope with the humidity change that occurs. Further, when the outside temperature is used as a reference, there is a problem that it cannot cope with a change in the inside temperature, and in any case, stable control cannot be performed.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of finely controlling the toner density in accordance with the state of the in-machine environment of the image forming apparatus. To do.

  In order to achieve the above object, in the present invention, a developing device for developing an electrostatic latent image using a developer having toner, an outside temperature / humidity detecting unit for detecting outside temperature and humidity, It has a correction table in which a correction value for correcting the control reference value for controlling the density to a preset value based on the temperature and humidity outside the machine is set, and based on the correction table, the outside of the machine An image forming apparatus comprising: a control unit that extracts a correction value corresponding to a detection result of the temperature / humidity detection unit and corrects a control reference value based on the correction value to control a toner density; The apparatus further includes state detection means for detecting the state of the in-machine environment of the apparatus, and a plurality of correction tables are set in advance corresponding to the state of the in-machine environment of the image forming apparatus, and the control means sets the control reference value. When correcting The correction table corresponding to the detection result is selected from the plurality of types of correction tables based on the detection result detected by the state detection means, and the correction value is extracted using the selected correction table. .

  According to this configuration, a plurality of types of correction tables are set in advance according to the state of the in-machine environment of the image forming apparatus. In correcting the control reference value, a correction table corresponding to the detection result is selected from a plurality of types of correction tables based on the detection result detected by the state detection unit. The correction value is extracted using the correction value, and the control reference value is corrected by the correction value. Therefore, since the corrected control reference value is determined in consideration of the state of the in-machine environment of the image forming apparatus and the temperature and humidity outside the apparatus, the corrected control reference value is determined according to the state of the in-machine environment of the image forming apparatus. The toner density can be finely controlled.

  In the present invention, the state detection unit detects an in-machine temperature in the vicinity of the developing device, and a plurality of types of correction tables are set corresponding to the in-machine temperature. According to this configuration, since a plurality of types of correction tables set in advance corresponding to the in-machine temperature in the vicinity of the developing device are set, the correction value is extracted in consideration of the in-machine temperature in the vicinity of the developing device. can do. Therefore, the toner density can be finely controlled in accordance with the temperature inside the apparatus.

  In the present invention, the state detection unit detects the in-machine humidity in the vicinity of the developing device, and a plurality of correction tables are set corresponding to the in-machine humidity. According to this configuration, since a plurality of types of correction tables set in advance corresponding to the in-machine humidity in the vicinity of the developing device are set, the correction value is extracted in consideration of the in-machine humidity in the vicinity of the developing device. can do. Accordingly, it is possible to finely control the toner density in accordance with the humidity inside the apparatus.

  In the present invention, the state detection means detects the number of continuous sheets of recording paper developed by the developing device, and a plurality of types of correction tables are set corresponding to the number of continuous sheets to be passed. It is characterized by. According to this configuration, since a plurality of types of correction tables set in advance corresponding to the number of continuous sheets of recording paper developed by the developing device are set, the number of continuous sheets passed by the developing device is sufficient. The correction value can be extracted in consideration of the above. Therefore, it is possible to finely control the toner density in accordance with the number of continuous sheets.

  According to the configuration of the present invention, it is possible to obtain an image forming apparatus capable of finely controlling the toner density in accordance with the state of the in-machine environment of the image forming apparatus itself.

(Embodiment)
A specific embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a schematic configuration diagram showing a schematic configuration when applied to a copying machine as an image forming apparatus using a developing device according to an embodiment of the present invention.

  As shown in FIG. 1, a copying machine 1 serving as an image forming apparatus includes a document conveying unit 3, an image reading unit 2, an image forming unit 4 for forming an image on a recording sheet P, a fixing unit 5, And a paper feed means 6 on which the recording paper P is stacked and stored. Further, a paper transport device 7 is formed that transports the recording paper P to the paper discharge unit 71 via the image forming unit 4 and the fixing unit 5.

  As is well known, the image reading means 2 irradiates light from an exposure lamp to the original that has been conveyed from the original conveying means 3 when it passes over the contact glass. Then, the reflected light is guided to a photoelectric conversion unit including a CCD sensor or the like through a reflecting mirror, thereby reading and reading the image information of the document.

  The document conveying unit 3 includes a document placing table 31 for placing a document, a document feeding unit that feeds a document loaded on the document placing table 31, and a fed document to the image reading unit 2. A document feed conveyance path for performing the document reading, and a document discharge section 32 for discharging the read document.

  The paper feed means 6 includes a plurality of paper feed cassettes 61 in which the recording paper P is accommodated, and from the paper feed cassette 61 selected from among the plurality of paper feed cassettes 61 by the rotation operation of the pickup roller 62. The recording paper P is sent out to the paper transport device 7 side. With this configuration, the recording paper P is reliably fed to the paper transport device 7 one by one. Each of these paper feed cassettes 61 is configured to be pulled out or detachable from the copying machine 1.

  The recording paper P fed to the paper transport device 7 is nipped (gripped) by a drive roller 73 provided on the transport path 72 and a driven roller 74 disposed opposite to the drive roller 73. Sequentially conveyed toward the image forming unit 4. The image forming unit 4 forms a predetermined toner image on the recording paper P by an electrophotographic process. For example, a photosensitive member 41 that is an image holding member that is rotatably supported in a predetermined direction (in the direction of an arrow in the drawing), and a charging device 42 and an exposure device around the photosensitive member 41 along the rotational direction. A device 43, a developing device 8, a transfer device 45, a cleaning device 46, and a charge eliminating device 47 are provided.

  The charging device 42 includes a charging wire to which a high voltage is applied. By applying a predetermined potential to the surface of the photoconductor 41 by corona discharge from the charging wire, the surface of the photoconductor 41 is uniformly charged. It is done. The exposure device 43 irradiates the photoconductor 41 with light based on the image data of the original read by the image reading means 2, thereby selectively attenuating the surface potential of the photoconductor 41, and this photosensitivity. An electrostatic latent image is formed on the surface of the body 41. Next, toner is attached to the electrostatic latent image by the developing device 8 to form a toner image on the surface of the photoconductor 41, and the toner image on the surface of the photoconductor 41 is transferred from the photoconductor 41 to the transfer device by the transfer device 45. 45 is transferred onto the recording paper P supplied between the two.

  The recording paper P to which the toner image is transferred is conveyed from the image forming unit 4 toward the fixing unit 5. The fixing unit 5 is disposed on the downstream side of the image forming unit 4 in the sheet conveyance direction. The recording paper P onto which the toner image has been transferred in the image forming unit 4 is formed by a heating roller 51 provided on the fixing unit 5 and rotatably supported by a shaft, and a pressure roller 52 pressed against the heating roller 51. It is conveyed to the fixing nip. Then, the toner image is fixed on the recording paper P by being heated and pressurized in the fixing nip. Next, the recording paper P on which the image is formed in the fixing unit 5 from the image forming unit 4 is discharged onto the paper discharge unit 71. On the other hand, after the transfer, the toner remaining on the surface of the photoconductor 41 is removed by the cleaning device 46, and the residual charge on the surface of the photoconductor 41 is removed by the charge eliminating device 47. The photosensitive member 41 is charged again by the charging device 42, and image formation is performed in the same manner.

Next, the configuration of the developing device will be described with reference to FIG. FIG. 2 is a partial cross-sectional view showing a schematic configuration of the developing device 8 used in the copying machine 1 shown in FIG.
The developing device 8 includes a developing unit 80a, a stirring unit 80 including a stirring screw 80b, 80c of a lateral circulation stirring system that circulates a two-component developer composed of toner and a carrier while mixing and stirring, and a toner concentration detection sensor ( (Not shown). Then, the toner supplied intermittently from the toner supply means 9 through the toner intake port 80d into the stirring unit 80 is conveyed to the developing roller 80a while being frictionally charged by the stirring screws 80b and 80c of the stirring unit 80, and is developed by the developing roller 80a. Toner is supplied to the photoreceptor 41.

  The toner replenishing means 9 includes a box-shaped container main body 91 that opens upward, a lid 92 that closes the upper opening of the container main body 91, and an agitating blade (in the container main body 91) that stirs toner. (Not shown) and the like, and is located on the side of the developing device 8 opposite to the photosensitive member 41. The container main body 91 includes a relatively large-capacity storage unit (not shown) in which the toner is stored, a communication unit 93 provided in the upper part of the storage unit on the developing device 8 side in communication with the storage unit, and the toner. And a sending unit 94.

  The toner delivery unit 94 is a portion where toner to be replenished to the developing device 8 is temporarily stored, and is positioned above a toner intake port 80d provided on one side of the developing device 8. The toner delivery section 94 is formed in an elongated shape substantially parallel to the axis of the photosensitive member 41, and a toner replenishing port 96 is provided at the bottom portion 95 so as to face a toner intake port 80 d as a toner replenishing opening of the developing device 8. . Further, the toner delivery part 94 is formed at a shallower bottom than the storage part, and is formed so that excessive toner pressure is not generated around the bottom part 95, particularly around the toner supply port 96. Further, the toner delivery unit 94 is formed in a substantially semicircular shape in cross section except for the periphery of the toner supply port 96, while the bottom is formed in a substantially flat shape in the periphery of the toner supply port 96. A transfer screw 97 (transfer means) is installed between the opposing side walls of the container main body 91 along the longitudinal direction.

  The transfer screw 97 is for transferring the toner conveyed and stored in the toner delivery unit 94 toward the toner supply port 96. The transfer screw 97 corresponds to a transfer rotary shaft 97a that is installed between the front and rear opposing walls of the container body 91 and rotates, a spiral blade 97b that protrudes from the outer peripheral surface of the transfer rotary shaft 97a, and a toner supply port 96. And a paddle 97c protruding from the outer peripheral surface of the transfer rotating shaft 97a. The transfer screw 97 is formed to have a relatively small diameter, and is set so that the amount of toner conveyed in one rotation is relatively small.

  The transfer rotating shaft 97a is rotationally driven by a driving unit, and the driving unit is controlled by a control unit as will be described later, and is configured to rotate counterclockwise in FIG. The spiral blade 97b conveys the toner toward the toner replenishing port 96 as the transfer rotation shaft 97a rotates, and is spirally wound in the reverse direction with a portion corresponding to the toner replenishing port 96 as a boundary. It is configured. When the developing device 8 is not filled with toner, the paddle 97c sends out the toner conveyed by the spiral blade 97b to the toner supply port 96 and the developing device 8 is filled with toner. The toner (excess toner) that has been transported excessively is discharged to the communicating portion 93, and is formed as a flat plate-like body. The paddle 97 c has a length substantially equal to the diameter of the transfer screw 97.

  A shutter member (not shown) for closing the toner replenishing port 96 is slidably provided below the toner replenishing port 96, and the shutter member is attached when the toner replenishing means 9 is attached to the copying machine 1 main body. Is configured to slide to open the toner supply port 96.

  FIG. 3 is a block diagram showing a schematic configuration of the copying machine shown in FIG. The copying machine 1 includes an image reading unit 2, a document conveying unit 3, an image forming unit 4 having a developing device 8, a fixing unit 5, a sheet feeding unit 6, and a sheet conveying unit 7. Further, an operation display unit 10 that functions as various input key switches and the like and a control unit 11 that controls the entire copying machine 1 are provided. The control means 11 controls the density of toner in the developing device 8 to be described later. The operation display unit 10 displays an operation unit 101 including a print key for inputting a print instruction, a numeric keypad for inputting the number of prints, and the like, functions that can be operated by the copier 1, trouble situations such as a paper jam, and the like. And a display device 102 such as a liquid crystal panel.

  Further, according to the present invention, the copying machine 1 includes an outside temperature / humidity detection unit 12 including a temperature sensor 12a for detecting the temperature outside the machine and a humidity sensor 12b for detecting humidity, and the state of the in-machine environment of the copying machine 1. The state detection means 13 for detecting is provided. Further, in order to detect the toner concentration in the developing device 8, for example, the toner concentration detection sensor 14 formed of a magnetic permeability sensor and the like, and to replenish the toner, the transfer rotation shaft 97 a of the toner delivery unit 94 is rotationally driven. And a driving means 15 comprising a stepping motor or the like. Here, the state of the in-machine environment is a factor that affects the control of the toner density, for example, the in-machine temperature, the in-machine humidity, and the number of continuous sheets.

  As the state detection means 13, an in-machine temperature sensor 13 a that detects the state of the in-machine environment, for example, the in-machine temperature in the vicinity of the developing device 8 can be used. Further, as the state detection means 13, an in-machine humidity sensor for detecting the in-machine humidity in the vicinity of the developing device 8, or a continuous paper detecting number of sheets of recording paper P developed by the developing device 8 per predetermined time. The paper number detecting means or the like can be used alone or in combination.

  The control means 11 includes a ROM in which a program for controlling the operation of the copying machine 1 and the like are stored in addition to performing a main arithmetic function. Further, the control means 11 is a microcomputer or the like having a built-in storage unit such as a RAM for temporarily storing data as a work area of each program and storing image data of the original obtained by the image reading means 2. It is configured. When a start key (not shown) of the operation display unit 10 is pressed, the control unit 11 sends a control signal for performing a copying operation to the document conveying unit 3, the image reading unit 2, the sheet feeding unit 6, the image forming unit 4, and the fixing unit. 5. Output to each block of the paper transport device 7 to control its operation. Further, as will be described later, the control unit 11 stores various programs for controlling the toner density, information, various collected data, and the like in a storage unit and controls them. Further, the control unit 11 is set with a correction value Q for correcting the control reference value for controlling the toner density from the temperature and humidity outside the apparatus to an appropriate control reference value, as shown in FIG. 16 is stored.

  FIG. 4 is a conceptual diagram showing the concept of a correction table for correcting the control reference value V. In accordance with the present invention, a plurality of types of correction tables 16 corresponding to the state of the in-machine environment of the copying machine 1 are set in advance as the correction table 16. For example, when the in-machine temperature sensor 13a is used as the state detection means 13, a plurality of types of correction tables 16 corresponding to a certain range of the in-machine temperature are set. For example, when the in-machine temperature is Y, a correction table (A) applied when Y <31 ° C., a correction table (B) applied when 31 ° C ≦ Y <35 ° C., and 35 ° C ≦ Y < A correction table (C) applied when 39 ° C. and a correction table (D) applied when 39 ° C. ≦ Y are set. Each of the correction tables (A) to (D) is set so that a predetermined correction value Q can be extracted (determined) from the temperature and humidity outside the apparatus.

  Next, control of the toner density according to the characteristic part of the present invention will be described with reference to FIG. 5 and FIGS. 1 to 4 described above. FIG. 5 is a flowchart for explaining control of the toner density of the copying machine shown in FIG.

  Thus, according to the present invention, the toner replenishment to the developing device 8 is performed by the toner concentration detection sensor 14, the outside temperature / humidity detection unit 12 that detects the temperature and humidity outside the machine, and the in-machine temperature sensor that is the state detection means 13. It is controlled by the control means 11 based on the detection result by 13a.

  First, when a power supply (not shown) is turned on to operate the copying machine 1, warming up is performed. That is, a heating source (not shown) disposed in the heating roller 51 in order to heat the surface temperature of the heating roller 51 to a fixing temperature suitable for fixing, for example, in a range of 180 ° C. ± 5 ° C. to 10 ° C. Energize and heat. By this heating, the heating roller 51 is heated, and when it reaches a preset proper fixing temperature, for example, 180 ° C., warming up is stopped. A ready display for image formation is displayed on the display device 102 of the operation display unit 10, and various settings relating to copying can be accepted. For example, if there is no copy instruction, the process shifts to standby control after a predetermined time has elapsed. Thereafter, various settings are made from the operation display unit 10, and when it is detected that the start key has been pressed thereafter, image processing is started in step S1, and normal image forming processing is performed.

  In parallel with the image forming process described above, when the developing device 8 is driven in step S2 according to the present invention, the process proceeds to step S3. In step S3, the in-machine temperature sensor 13a, which is the state detection means 13, is used. Is detected, and the in-machine temperature Y as the detection result is transmitted to the control means 11. In step S4, the control means 11 selects the correction table 16 corresponding to the detection result from among a plurality of types of correction tables 16 (A) to (D) based on the in-machine temperature Y. For example, when the in-machine temperature Y is 28 ° C., the correction table (A) is selected, and the process proceeds to step S5.

  In step S <b> 5, the temperature and humidity outside the machine are detected by the temperature sensor 12 a and the humidity sensor 12 b of the outside temperature and humidity detection unit 12, and the detection result is transmitted to the control means 11. In step S6, the control means 11 extracts the correction value Q from the temperature and humidity outside the apparatus using the correction table (A) selected in step S4, and proceeds to step S7. In step S7, the control means 11 performs an operation (V0 + Q = V) for correcting the correction value Q to the initial control reference value V0, determines the control reference value V, and proceeds to step S8.

  In step S8, for example, the toner concentration detection sensor 14 including a magnetic permeability sensor detects the toner concentration in the developing device 8, and the detection result (X: the output value of the toner concentration detection sensor 14) is transmitted to the control means 11. Is done. In this case, when the magnetic permeability sensor is used, the output value X increases as the toner density decreases. Then, the control unit 11 compares the control reference value V determined in step S7 with the output value X that is the detection result detected by the toner density detection sensor 14. When the toner density is low and the output value X is larger than the control reference value V (X> V: Yes in step S8), the process proceeds to step S9. In step 9, in order to replenish the toner by the toner replenishing means 9, the driving rotating shaft 97a is rotationally driven by the driving means 15 to replenish the toner. Further, when the toner density is high and the output value X is equal to or smaller than the control reference value V (X ≦ V: No in step S8), toner supply by the toner supply means 9 is performed. I will not.

  Then, in step 10, it is confirmed whether or not the image forming process for the number of copies (set number) set by the control means 11 has been completed. If not (NO in step S10), again, The process proceeds to step S3 to control the toner density. If completed (YES in step S10), the copying process is terminated and a transition is made to the ready mode.

  According to the present embodiment having the above-described configuration, a plurality of types of correction tables 16 set in advance according to the state of the in-machine environment of the copying machine 1 that is an image forming apparatus are set. In correcting the control reference value V, first, a correction table 16 corresponding to the detection result is selected from a plurality of types of correction tables 16 based on the detection result detected by the state detection means 13. . Thereafter, the correction value Q is extracted using the selected correction table 16, and the initial control reference value V0 is corrected by the correction value Q. Therefore, the corrected control reference value V is determined in consideration of the state of the internal environment of the copying machine 1 and the temperature and humidity outside the apparatus. The toner density can be finely controlled.

  In addition, since a plurality of types of correction tables 16 set in advance corresponding to the in-machine temperature in the vicinity of the developing device 8 are set, the correction value is extracted in consideration of the in-machine temperature in the vicinity of the developing device 8. be able to. Therefore, the toner density can be finely controlled in accordance with the temperature inside the apparatus.

The above-described embodiment is a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention.
For example, in the above-described embodiment, the copying machine has been described as an example. However, the present invention can be applied to, for example, a facsimile machine, a multifunction machine having various functions such as a copying function, a printer function, a scanner function, and a facsimile function. It is applicable to.

  In the above-described embodiment, the drum-shaped photoconductor 41 is used. However, the shape of the photoconductor 41 is not limited, and a known shape other than the above-described drum shape can be used. Examples of the shape include a sheet shape, a belt shape, and a web shape.

  In the above-described embodiment, the state detection unit detects the in-machine temperature in the vicinity of the developing device. Instead, the state detection unit detects the in-machine humidity in the vicinity of the developing device. A plurality of types may be set corresponding to the humidity. According to this configuration, since a plurality of types of correction tables set in advance corresponding to the in-machine humidity in the vicinity of the developing device are set, the correction value is extracted in consideration of the in-machine humidity in the vicinity of the developing device. can do. Accordingly, it is possible to finely control the toner density in accordance with the humidity inside the apparatus.

  The state detecting means detects the number of continuous sheets of recording paper developed by the developing device, and the correction table includes a plurality of correction tables corresponding to the number of continuous sheets, for example, the number of continuous sheets per fixed time. The type may be set. According to this configuration, since a plurality of types of correction tables set in advance corresponding to the number of continuous sheets of recording paper developed by the developing device are set, the number of continuous sheets passed by the developing device, that is, The correction value can be extracted with sufficient consideration of the moisture absorption state of the recording paper P or the like. Therefore, it is possible to finely control the toner density in accordance with the number of continuous sheets.

  Further, the state detection means detects the temperature and / or humidity in the vicinity of the developing device and the number of continuous sheets to be passed, and considers the temperature and / or humidity and the number of sheets to be passed as a correction table. A plurality of types of correction tables may be set. With this configuration, the toner density can be controlled more finely.

  As an application example of the present invention, there is an image forming apparatus provided with a developing device that develops an electrostatic latent image formed on a photoreceptor using a developer having toner.

1 is a schematic configuration diagram showing a schematic configuration when applied to a copying machine as an image forming apparatus using a paper feeding device according to an embodiment of the present invention. FIG. 2 is a partial cross-sectional view illustrating a schematic configuration of a developing device used in the copying machine 1 illustrated in FIG. 1. FIG. 2 is a block diagram illustrating a schematic configuration of the copier illustrated in FIG. 1. It is a conceptual diagram which shows the concept of the correction table which correct | amends a control reference value. 3 is a flowchart for explaining control of toner density of the copying machine shown in FIG. 1.

Explanation of symbols

P ... recording paper, Q ... correction value, V ... control reference value, V0 ... initial control reference value, Y ... in-machine temperature, 1 ... copier (image forming apparatus), 8 ... developing device, 11 ... control means, 12 ... External temperature / humidity detection unit, 13 ... Status detection means, 16 ... Correction table, 41 ... Photoconductor

Claims (4)

A developing device that develops an electrostatic latent image using a developer having toner, an outside temperature / humidity detecting unit that detects outside temperature and humidity, and a control reference value for controlling the density of the toner, It has a correction table in which a correction value for correcting to a preset value based on the temperature and humidity outside the machine is set, and corresponds to the detection result of the outside temperature and humidity detection unit based on the correction table An image forming apparatus comprising: a control unit that extracts the correction value, corrects the control reference value based on the correction value, and controls the toner density;
The image forming apparatus further includes a state detection unit that detects a state of the in-machine environment of the image forming apparatus, and a plurality of types of the correction table are set in advance corresponding to the state of the in-machine environment of the image forming apparatus. When correcting the control reference value, a correction table corresponding to the detection result is selected from the plurality of types of correction tables based on the detection result detected by the state detection unit, and the selected correction is performed. An image forming apparatus characterized in that the correction value is extracted using a table.   The image forming apparatus according to claim 1, wherein the state detection unit detects an internal temperature in the vicinity of the developing device, and a plurality of types of the correction tables are set corresponding to the internal temperature. apparatus.   The image forming apparatus according to claim 1, wherein the state detection unit detects an in-machine humidity in the vicinity of the developing device, and a plurality of types of correction tables are set corresponding to the in-machine humidity. apparatus.   The state detection means detects the number of continuous sheets of recording paper developed by the developing device, and a plurality of types of correction tables are set corresponding to the number of continuous sheets to be passed. The image forming apparatus according to claim 1.

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