JP6526302B2 - Image forming device - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer or the like using an electrophotographic method or an electrostatic recording method.

  Among image forming apparatuses, a so-called electrophotographic digital laser printer is known. In a developing device included in such an image forming apparatus, a one-component developer containing magnetic toner as a main component or a two-component developer containing non-magnetic toner and a magnetic carrier as main components is used. In particular, in an image forming apparatus for forming a full color or multi-color image, most of them use a two-component developer from the viewpoint of color and the like of the image.

  Particularly important in a two-component developer, toner replenishment control is raised. The two-component developer is composed of a toner and a carrier, and when an image is formed, the TD ratio which is the ratio of the toner and the carrier changes when the toner is consumed. Since the charging characteristic of the toner changes according to the value of the TD ratio, it is required to replenish the toner so as to maintain the charging characteristic of the toner. The toner bottle for replenishing the toner is provided separately from the developing device, and when the toner in the toner bottle is exhausted, it is replaced with a new toner bottle.

  As a means for determining that the toner in the toner bottle has run out (no toner), there is a method as described in Patent Document 1. Specifically, a toner density sensor for detecting the TD ratio of the two-component developer is provided in the developing device, and the absence of toner is determined according to the value. Furthermore, in order to increase the accuracy without toner, it is confirmed whether the TD ratio of the two-component developer increases from the value of the toner density sensor after toner replenishment, and the method for judging the absence of toner based on the result ( There is a toner remaining amount confirmation sequence).

Patent Document 1: Japanese Patent Application Laid-Open No. 2005-062848

  However, in the case of the configuration in which the above-described toner remaining amount confirmation sequence is performed, the following problems occur.

  As the remaining amount of toner in the toner bottle decreases (immediately before toner absence), the amount of toner that can be supplied into the developing device decreases. For this reason, even in the case of an image with a small amount of toner consumption, the TD ratio of the two-component developer decreases, and the toner remaining amount confirmation sequence is activated.

  However, even if the toner remaining amount confirmation sequence is performed, the TD ratio of the two-component developer does not increase because the amount of toner supplied to the developing device is small. For this reason, the toner remaining amount confirmation sequence may be repeated more than necessary. In this case, there is a problem that downtime frequently occurs due to the toner remaining amount confirmation sequence until "no toner" is displayed. That is, with regard to the toner remaining amount confirmation sequence, there are problems in achieving both the control time and the detection accuracy of “toner present” and “toner absent”.

  Here, if the toner remaining amount confirmation sequence is simply limited to simply reduce the downtime, the detection accuracy of the toner density may be degraded.

  An object of the present invention is to suppress a decrease in the accuracy of toner residual amount determination while shortening the down time by the toner residual amount confirmation sequence as much as possible.

  A representative configuration of the present invention for achieving the above object is an image forming apparatus capable of performing an image forming operation for forming an image on a recording material, which is a developer including an image carrier, toner, and carrier. A developer container for containing the developer, a developer conveying portion for conveying the developer contained in the developer container, and a developer for carrying the developer for developing the electrostatic latent image formed on the image carrier A developing device having an agent carrier, and the toner of the developer contained in the developer container by detecting the magnetic permeability of the developer provided in the developing device and contained in the developer container A magnetic permeability sensor for detecting a toner concentration as a ratio of a carrier, a toner container which is provided so as to be attachable to a mounting portion of the image forming apparatus and which accommodates the toner for supplying the developing container, the toner In a container A drive motor rotatably driven to supply the toner to the developing container, and the drive motor being accommodated in the developing container detected by the magnetic permeability sensor while the image forming operation is being performed The first detected toner density, which is the toner density of the developer, and the target toner density, which is the target toner density of the developer to be stored in the developing container, and the image ratio of the image formed on the recording material The first operation of rotationally driving the drive motor by the number of rotations based on the information related to the second aspect, and the second operation of rotationally driving the drive motor by the predetermined number of rotations in the state where the image forming operation is interrupted And the control unit is configured to control the first detected toner concentration to be lower than the target toner concentration, and to control the first detected toner concentration and the target toner concentration. The image forming operation is interrupted to execute the second operation when the predetermined condition including the absolute value of the minute is higher than the predetermined threshold is performed, and the control unit performs the second operation once. Each time the drive motor is driven to rotate by the predetermined number of rotations by one execution of the second operation each time it is executed, it is detected by the magnetic permeability sensor while the image forming operation is interrupted. Transitioning to a state in which the interrupted image forming operation can be resumed based on the second detected toner concentration which is the toner concentration of the developer stored in the developer container; and And selecting and executing one of the plurality of toner containers including prompting replacement of the toner container attached to the unit.

  Another configuration is an image forming apparatus capable of performing an image forming operation for forming an image on a recording material, the image carrier, a developing container for containing a developer including toner and carrier, and the developing container A developer transport unit for transporting the developer contained in the developer, and a developer carrier for carrying the developer for developing the electrostatic latent image formed on the image carrier; And detecting a magnetic permeability of the developer contained in the developing container, provided in the developing device, and detecting a toner concentration as a ratio of toner and carrier of the developer contained in the developing container. Magnetic permeability sensor, a toner container which is detachably mounted to the mounting portion of the image forming apparatus and stores the toner to be supplied to the developing container, and the toner stored in the toner container. Said development The toner concentration of the developer contained in the developer container detected by the magnetic permeability sensor while the image forming operation is being performed. Only the time based on the first detected toner density, the target toner density which is the target toner density of the developer to be stored in the developing container, and information on the image ratio of the image formed on the recording material A control unit capable of executing a first operation for rotationally driving a drive motor and a second operation for rotationally driving the drive motor for a predetermined time while interrupting the image forming operation; The first detection toner density is lower than the target toner density, and the absolute value of the difference between the first detection toner density and the target toner density is higher than a predetermined threshold. When the predetermined condition including the condition is satisfied, the image forming operation is interrupted to execute the second operation, and the control unit performs the second operation once. The toner of the developer contained in the developer container detected by the magnetic permeability sensor while the image forming operation is interrupted after the drive motor is rotationally driven for the predetermined time by execution. Transitioning to a state capable of resuming the interrupted image forming operation based on the second detected toner density which is density, and promoting replacement of the toner container mounted on the mounting portion It is characterized in that one of the plurality is included and executed.

  According to the above configuration, it is possible to suppress the decrease in the accuracy of the toner remaining amount determination while shortening the down time by the toner remaining amount checking sequence as much as possible.

FIG. 2 is a cross-sectional view showing a detailed configuration of an image forming unit. FIG. 1 is a schematic cross-sectional view showing the entire configuration of an image forming apparatus. Explanatory drawing which shows the structure of a toner bottle. FIG. 7 is a diagram for explaining TD ratio unevenness of the developer in the developing device of the first embodiment. The figure which shows the formation timing of a patch image. The figure which shows the flowchart of 1st Embodiment. Explanatory drawing from toner replenishment of 1st Embodiment to TD ratio detection. FIG. 7 is a diagram showing determination after ΔTD ratio (END) detection according to the first embodiment. FIG. 8 is a diagram showing the relationship between a target TD ratio and a toner presence determination value in the second embodiment. The figure which shows the flowchart of 4th Embodiment. The table of the relationship between delta TD ratio (END) of a 4th embodiment, and the number of times of driving of a replenishment motor.

First Embodiment
A first embodiment of the present invention will be described using the drawings. FIG. 2 is a schematic cross-sectional view showing the entire configuration of the image forming apparatus. The image forming apparatus of the present embodiment is a digital type electrophotographic image forming apparatus. Hereinafter, the image forming apparatus will be described in detail.

  As shown in FIG. 2, an endless intermediate transfer belt 81 (ITB) traveling in the arrow X direction is disposed in the image forming apparatus. The intermediate transfer belt 81 is stretched by three rollers of a drive roller 37, a tension roller 38, and a secondary transfer inner roller 39.

  The transfer material P taken out of the feeding cassette 60 is supplied to the transport roller 61 through the pickup roller, and is further transported to the left in FIG.

  The image forming portion IP is disposed above the intermediate transfer belt 81. FIG. 1 is a cross-sectional view showing the detailed configuration of the image forming unit. The image forming unit includes a drum-shaped photosensitive drum 1 (image carrier) rotatably disposed.

  The photosensitive drum 1 has a support shaft (not shown) at its center, and is rotationally driven by a drive unit (not shown) in the direction of the arrow R1 about this support shaft. The rotational speed of the photosensitive drum 1 in the present embodiment is 110 mm / s. Around the photosensitive drum 1, process devices such as a charging roller 11, a developing device 2 (developing device), a primary transfer roller 14, and a cleaning device 15 are disposed.

  The charging roller 11 (primary charger) contacts the surface of the photosensitive drum 1, and uniformly charges the surface to a predetermined polarity and potential. The charging roller 11 is configured in a roller shape as a whole. The charging roller 11 is pressed against the surface of the photosensitive drum 1 with a predetermined pressing force, and the charging roller 11 is driven to rotate as the photosensitive drum 1 rotates in the direction of the arrow R1.

  A bias voltage is applied to the core metal of the charging roller 11 by a charging bias power supply (not shown), whereby the surface of the photosensitive drum 1 is contact-charged uniformly and uniformly.

  In the present embodiment, a bias voltage in which 1.5 kVpp of DC voltage and AC voltage is superimposed is applied to the core metal of the charging roller 11. By applying an AC voltage, the potential on the photosensitive drum 1 can be converged to the same value as the DC voltage. For example, the potential of the surface of the photosensitive drum 1 after charging when the direct current voltage is −600 V is −600 V.

  A scanner unit 12 (exposure unit) is disposed downstream of the charging roller 11. A laser beam corresponding to an image signal is emitted from the scanner unit 12 to the photosensitive drum 1. Thereby, an electrostatic image is formed on the photosensitive drum 1.

  The intensity of the laser beam of the scanner unit 12 can be changed in the range of 0 to 255. The latent image potential is changed by changing the laser light intensity. In this embodiment, the potential on the photosensitive drum 1 when the laser light intensity: L is changed to 0 to 255 is V (L) (V (L = 0) to V (L = 255)).

  The developing device 2 is disposed downstream of the scanner unit 12. The developing device 2 accommodates a two-component developer using nonmagnetic toner and magnetic carrier. In this embodiment, a two-component developing method using a two-component developer is used. Further, in the present embodiment, toner of negative charge is used.

  The inside of the developing device 2 is divided into a developing chamber 212 and a stirring chamber 211 by a partition 213 extending in the vertical direction.

  In the developing chamber 212, a nonmagnetic developing sleeve 232 (developer carrier) is disposed. A magnet 231 (magnetic field generating means) is fixedly arranged in the developing sleeve 232. The magnet 231 has a configuration of about three or more poles. In the present embodiment, a 5-pole magnet is used. As described above, at least the developing unit for developing the electrostatic latent image includes the developing device 2 and the developing sleeve 232.

  A first conveying screw 222 and a second conveying screw 221 are disposed in the developing chamber 212 and the stirring chamber 211, respectively, as developer stirring and conveying means.

  The developing sleeve 232, the first conveying screw 222, and the second conveying screw 221 are driven by the developing drive motor 27.

  The first conveying screw 222 stirs and conveys the developer in the developing chamber 212. Further, the second conveying screw 221 stirs and conveys the toner supplied from the toner bottle 7 and the developer already in the developing device 2. By these stirring and conveyance, the toner concentration of the developer in the developing device 2 is made uniform.

  In the stirring chamber 211, an inductance sensor 26 (concentration detection unit) is provided. The inductance sensor 26 detects toner concentration in the developing device (ratio of toner to carrier: TD ratio).

  The arrangement position of the inductance sensor 26 is such that the toner supplied from the toner bottle 7 by the second conveyance screw 221 and the developer already in the developing device 2 are stirred and conveyed to equalize the toner concentration of the developer. Place the developer at a position where it can be detected. By doing this, detection of the toner concentration of the developer by the inductance sensor 26 can be accurately performed.

  In the partition wall 213 between the developing chamber 212 and the agitating chamber 211, a developer passage is formed which allows the developing chamber 212 and the agitating chamber 211 to communicate with each other at the front end and the back end in the figure. For this reason, the developer conveyed by the conveyance force of the first conveyance screw 222 and the second conveyance screw 221 circulates between the developing chamber 212 and the stirring chamber 211 through the developer passage.

  Specifically, the developer in the developing chamber 212 in which the toner is consumed by development and the toner concentration of the developer is lowered moves from the one developer passage to the stirring chamber 211. Since the toner is supplied from the toner bottle 7 to the agitating chamber 211, the toner concentration of the developer is recovered in the agitating chamber 211. Then, the developer whose toner concentration has recovered moves from the other developer passage to the developing chamber 212.

  The two-component developer stirred by the first conveyance screw 222 in the developing device 2 is restrained by the magnetic force of the conveyance magnetic pole (pick-up pole) N3 of the magnet 231 by the rotation of the development sleeve 232 while being restrained by the magnetic force. It is transported. Also, the developer is sufficiently restrained by the transport magnetic pole (cut pole) S2 having a magnetic flux density of a certain level or more, and is transported while forming a magnetic brush on the developing sleeve 232.

  Next, the developer layer thickness of the magnetic brush formed on the magnet 231 is adjusted to an appropriate length of the magnetic brush by cutting off the magnetic brush by the restriction blade 25. Thereafter, the developer is transported to the developing area facing the photosensitive drum 1 as the transport magnetic pole N1 and the developing sleeve 232 rotate. Here, in the developer, a magnetic brush is raised by the development pole S1 in the development area.

  Then, only the toner of the developer is transferred to the electrostatic image on the photosensitive drum 1 by the developing bias applied to the developing sleeve 232. Thus, a toner image corresponding to the electrostatic image is formed on the surface of the photosensitive drum 1.

  A predetermined developing bias is applied to the developing sleeve 232 from a developing bias power supply (not shown) as a developing bias output unit. In the present embodiment, a developing bias voltage in which a DC voltage (Dev DC = −500 V) and an AC voltage (Dev AC = 1.3 KVpp) are used as the developing sleeve 232 from the developing bias power supply.

  A toner bottle 7 is attached to the developing device 2 of the present embodiment. FIG. 3 is an explanatory view showing the configuration of the toner bottle.

  As shown in FIG. 3, a replenishment motor 73 (refilling drive unit) is disposed in the toner bottle 7 (refilling device). The lower toner conveyance screw 72 and the upper toner conveyance screw 71 in the toner bottle 7 are rotated by the replenishment motor 73.

  Then, when the replenishment motor 73 is driven, the lower toner conveyance screw 72 is rotated. The toner in the toner bottle 7 conveyed by the rotation of the lower toner conveyance screw 72 is supplied to the developing device 2 from a supply port 75 formed in the lower part of the toner bottle 7. By driving the replenishment motor 73, the upper toner conveyance screw 71 is also rotated simultaneously with the lower toner conveyance screw 72, and the toner on the upper portion of the toner bottle 7 is conveyed.

  Control of each part of the apparatus, such as rotation control of the replenishment motor 73 and calculation of the remaining replenishment amount, is performed by the CPU 101 of the control unit 100. Under the control of the control unit 100, based on the detection result of the inductance sensor 26, it is possible to execute a toner confirmation mode in which the image forming operation is interrupted to supply toner from the toner bottle 7 to the developing device 2.

  Further, the rotation detection of the replenishment motor 73 is performed by the rotation detection sensor 74. The rotation detection sensor 74 can detect each rotation of the screw as a unit. The CPU 101 controls the supply motor 73 to rotate by a predetermined amount of rotation. The control result by the control unit 100 is displayed as needed through the display 300 such as a display.

  Above the toner bottle 7, a toner bottle presence sensor 76 is disposed. The presence of the toner bottle 7 is determined by the presence of the toner bottle presence sensor 76.

  As shown in FIG. 2, a primary transfer roller 14 is disposed downstream of the developing device 2 in the rotational direction of the surface of the photosensitive drum 1. Both end portions of the primary transfer roller 14 are urged against the photosensitive drum 1 by a pressing member such as a spring (not shown).

  A cleaning device 15 is disposed downstream of the position of the primary transfer roller 14 in the rotational direction of the photosensitive drum 1. The cleaning blade in the cleaning device 15 removes the toner remaining on the photosensitive drum 1.

  An image density sensor 31 for detecting the density of the toner image formed on the intermediate transfer belt 81 is provided on the intermediate transfer belt 81.

  When the transfer material P taken out of the feeding cassette 60 is conveyed to the conveyance roller 41, the leading end of the transfer material P is once stopped by the conveyance roller 41. Then, the transfer material P is fed from the conveyance roller 41 in timing so that the toner image formed on the intermediate transfer belt 81 can be transferred to a predetermined position of the recording material.

  Next, in the area where the secondary transfer inner roller 39 and the secondary transfer outer roller 40 abut on the transfer material P, the toner of the above four colors is applied by the secondary transfer bias applied to the secondary transfer outer roller 40. The image is transferred onto the transfer material P.

  A cleaning device 50 is disposed downstream of the secondary transfer inner roller 39 in the transport direction of the intermediate transfer belt 81. The cleaning blade in the cleaning device 50 removes the toner remaining on the intermediate transfer belt 81.

  The transfer material P separated from the intermediate transfer belt 81 is conveyed to the fixing device 90. The toner image transferred onto the transfer material P is heated and pressurized by the fixing device 90. As a result, the toner image is melt mixed with the transfer material P and fixed on the transfer material P. The image density of the output image information on the transfer material P is calculated by the video counter 91 (image density calculation unit), and the data is transmitted to the control unit as a video count value.

  Thereafter, the transfer material P is discharged out of the image forming apparatus. In the present embodiment, the image forming apparatus can discharge an A4 size image at a maximum speed of 25 sheets per minute.

(Toner supply control)
Details of the toner supply control according to the present embodiment will be described.

  By developing the electrostatic image and consuming the toner, the toner concentration of the developer in the developing device 2 is reduced.

  For this reason, the toner supply control for supplying the toner from the toner bottle 7 to the developing device 2 is performed by the density control device. Thereby, the toner concentration of the developer is controlled as constant as possible, or the image density is controlled as constant as possible.

  In the present embodiment, the replenishment control is performed based on two pieces of information. The supply amount at the time of forming the Nth image will be described below.

  First, the video count value: Vc is calculated from the image information of the Nth output product, the calculated video count value is multiplied by the coefficient: A (Vc), and the video count replenishment amount: M (Vc) is calculated. calculate.

Equation 1 is
M (Vc) = Vc × A (Vc) (Equation 1)
It is.

  Here, the video count value when the image ratio: 100% (full-area solid black) image is output: Vc = 1023, and the video count value: Vc changes according to the image ratio.

  The second is the difference between the TD ratio calculated from the detection result of the inductance sensor 26 on the N−1th sheet: TD (Indc) and the target TD ratio: TD (target). ) To calculate the amount of inducted replenishment: M (Indc) according to the following equation 2.

Equation 2 is
M (Indc) = (TD (target)-TD (Indc)) x A (Indc) ... (Formula 2)
It is.

  Here, the coefficients A (Vc) and A (Indc) are stored in advance in the ROM 102.

  Target TD ratio: TD (target), that is, the toner density target value is recorded in the RAM 103, and it is possible to change the set value. Target TD ratio: Regarding the method of changing TD (target), in the present embodiment, an image pattern for image density detection (patch image Q) is formed for reference, and the image density is detected by the image density sensor 31. And the results have changed.

  FIG. 5 is a diagram showing the formation timing of the patch image. As shown in FIG. 5, a patch image Q is formed between images at predetermined intervals, and the image density is detected by the image density sensor 31. The patch image Q is always performed under the same latent image condition, and the toner density of the developed toner image is the same if the state of the developer is the same.

  Based on the detection value of the density of the patch image Q in the initial developer, the difference is obtained from the difference ΔD between the reference value and the measurement result. For example, the density of the patch image Q with the initial developer: D (initial) = 400, the density of the patch image Q measured when the image forming apparatus outputs the Xth sheet increases, and the density: D (X (X) In the case where) = 500, ΔD is obtained by the following equation 3.

Equation 3 is
ΔD (X) = D (X) −D (initial) = 100 (Equation 3)
It is.

  Here, the relationship between ΔD (X) and the target TD ratio: change width of TD (target): ΔTD (target) is recorded in advance in the ROM 102. From this recorded data, ΔTD (target) is calculated. Then, the target TD ratio: TD (target) is changed by adding and subtracting the calculated ΔTD (target).

  From the above-described video count replenishment amount: M (Vc) and two values, toner replenishment amount: M is calculated by the following equation 4.

Equation 4 is
M = M (Vc) + M (Indc) + M (remain) ... (Equation 4)
It is.

  M (remain) is the remaining supply amount which can not be supplied. The reason for the generation of the remaining supply amount is that, since the supply is performed in units of one rotation of the screw, a supply amount less than one rotation is integrated. Details will be described later. If M <0, then M = 0.

  Next, from the toner replenishment amount: M, the number of rotations of the replenishment motor 73: B is calculated. The amount by which the lower toner conveyance screw 72 makes one rotation and the toner is replenished to the developing device is recorded in advance in the ROM 102, and the number of rotations of the replenishment motor 73: B is calculated from the calculated toner replenishment amount: Do.

Equation 5 is
B = M / T (Equation 5)
It is.

  The decimal part of B is rounded down, and only positive part. Since the toner replenishment amount corresponding to the decimal point of B is not replenished, the remaining replenishment amount: M (remain) is calculated by Equation 6 below.

Equation 6 is
M (remain) = M-B x T (Equation 6)
It is.

  Based on B calculated by Equation 5, the replenishment motor 73 is driven to rotate B for the Nth sheet.

  As described in the item of the invention, regarding the toner remaining amount confirmation sequence (toner confirmation mode), the control time and the detection accuracy of “toner present” and “toner absent” are compatible. There are challenges. The contents of the task will be described concretely below.

  If the distribution of the TD ratio of the two-component developer in the developing device is not constant, the TD ratio detected by the toner concentration sensor may vary. For this reason, it may not be possible to correctly determine whether the TD ratio has increased due to toner replenishment.

  Here, the TD ratio unevenness will be described. FIG. 4 is a view for explaining the TD ratio unevenness of the developer in the developing device of the first embodiment.

  The measurement of TD ratio unevenness is performed in the following procedure. First, with no toner in the toner bottle 7, continuous output is performed under the condition of an image ratio of 10% (indicated by a dotted line (a)) or the image ratio of 80% (indicated by a broken line (b)). Next, after the detection TD ratio by the toner density sensor falls from 8% to 7%, the image ratio is continuously output at 0% (solid white image). At that time, transition of the TD ratio detected by the toner concentration sensor is shown in FIG. In the case where the image ratio is expressed as 100%, it indicates that a black solid image is output over the entire surface.

  It can be seen from FIG. 4 that the detection TD ratio has unevenness in the image ratio after output at 80%. When forming an image on the photosensitive drum 1 in the developing unit, the place where the toner is consumed and the place where the toner is supplied are different. Then, under the condition that the image ratio is high, it takes time for the distribution of the TD ratio of the two-component developer in the developing device 2 to be uniform. This is a factor which causes variation in the distribution of the TD ratio of the two-component developer in the developing device 2.

  As shown in FIG. 4B, even when the image ratio is high, the TD ratio distribution becomes uniform over time. However, as compared to the case where the image ratio is low, it takes a long time to become uniform, so it takes time for the remaining toner amount confirmation sequence.

  In addition, when there is unevenness in the detection TD ratio, it is possible to determine that there is toner if the amount of toner replenishment to be replenished is large. However, since it is not known how much the toner replenishment amount will come, there is a risk of oversupply. Therefore, there are problems in achieving both the control time of the toner remaining amount confirmation sequence and the accuracy of the toner absence confirmation.

(Detailed Description of Toner Level Check Sequence)
From here, the control for checking the absence of toner in the toner bottle, which is the feature of the present embodiment, will be described. The toner remaining amount confirmation sequence can be executed by the control unit 100. FIG. 6 is a diagram showing a flowchart of the first embodiment. The following will be described along the flowchart.

  First, conditions for entering a toner remaining amount confirmation sequence will be described. In the present embodiment, image formation is interrupted when the TD (Indc) N detected on the N-th sheet and the target TD ratio: TD (target) continuously satisfy the following Formula 7 (S1): (S2) The toner remaining amount confirmation sequence is executed (S3).

Equation 7 is
ΔTD ratio N = TD (Indc) N−TD (target) ≦ −1.0% (7)
It is.

  It is also possible to make it another number about the conditions of the value of -1.0% of (Formula 7), and the case where 3 sheets are continuously filled. In the present embodiment, the above condition is set as the condition not to enter into the toner remaining amount confirmation sequence carelessly at the time of outputting the entire area solid image of the image ratio: 100%.

  FIG. 7 is an explanatory view from toner replenishment to detection of the TD ratio according to the first embodiment. When the toner remaining amount confirmation sequence is carried out (S4), as shown in FIG. 7, the replenishment motor 73 is rotated 10 times, and the developing drive motor 27 is driven for 10 seconds (S5). The number of rotations and the time are determined by the toner replenishment amount and the time when the toner reaches the inductance sensor 26 after the toner replenishment.

  Thereafter, a detection TD ratio between 9 and 10 seconds after the start of rotation of the developing drive motor 27 is detected by the inductance sensor 26 (S8).

  Regarding the number of times of replenishment of the replenishment motor 73, the drive time of the development drive motor 27, and the timing of detecting the TD ratio by the inductance sensor 26, the replenishment amount of the toner bottle 7 or the developer from the replenishment opening 75 to the inductance sensor 26 is It is set by the transport time. It is important to optimize these values in accordance with the configuration of the image forming apparatus.

  A TD ratio detected by the inductance sensor 26 between 9 and 10 seconds after the start of rotation of the developing drive motor 27 is set as a detected TD ratio: TD (Indc) R. Then, it is determined whether the difference value between the detected TD ratio: TD (Indc) R and the target TD ratio: TD (target): ΔTD ratio (END) satisfies the relationship of Expression 8.

Equation 8 is
Δ TD ratio (END) = TD (Indc) R-TD (target) −-0.2% ... (Equation 8)
It is. In the present embodiment, −0.2% is set as the “toner presence determination value”.

  If the above formula 8 which is a judgment formula is satisfied, it is judged that "toner is present" (S8). In this case, the toner remaining amount confirmation sequence is ended, resumption of image formation is permitted (S9), and toner replenishment is ended (S10).

  If the above equation 8 is not satisfied in (S7), the process proceeds to (S11). In (S11), it is determined whether or not the ΔTD ratio (END) satisfies the relationship of Formula 9 below.

Equation 9 is
ΔTD ratio (END) = TD (Indc) R−TD (target) ≦ −0.9% (Expression 9)
It is. In the present embodiment, −0.9% is set as “the determination value without toner”.

  If the above formula 9 which is the judgment formula in (S11) is satisfied, it is judged that "toner is not present" (S12). Then, the toner remaining amount confirmation sequence is ended, and the image formation restart is stopped (S13). In this case, “Replace toner bottle” is displayed on the display 300 (S14).

  When the detected TD ratio detected in (S7) and (S11): TD (Indc) R does not satisfy either of the above-mentioned formula 8 and formula 9 (as a figure, it is larger than -0.9% -0.2% Is smaller) proceeds to (S15).

  FIG. 8 is a diagram showing the determination after ΔTD ratio (END) detection according to the first embodiment.

  As shown in FIG. 8, in the present embodiment, “ΔTr ratio” (END) ≧ −0.2% is set as “toner is present”. Further, if ΔTD ratio (END) ≦ −0.9%, “no toner” is set. And if -0.2%>. DELTA.TD ratio (END)>-0.9%, then "discriminatement decision" is made, and the number of times of accumulated replenishment of the replenishment operation of (S5) is repeated up to three times (predetermined number of times) of replenishment (S5) Perform the action.

  As described above, in the present embodiment, if the range of −0.2%> ΔTD ratio (END)> − 0.9%, the replenishment operation is re-executed. The reason for performing the replenishment operation again is that if unevenness occurs in the TD ratio of the developer in the developing device 2 (see FIG. 4B), whether the toner is reliably replenished (with toner) or It is because it can not be judged whether or not the toner is replenished (no toner).

  In this embodiment, if the range of −0.2%> ΔTD ratio (END)> − 0.9% from the range of the unevenness of the TD ratio in the result of FIG. However, other ranges may be used.

  Under the condition that the cumulative number of times of replenishment is less than 3 in (S15), the replenishment operation of (S5) is performed again. In this case, the ΔTD ratio (END) is detected again, and it is repeated to determine whether the value corresponds to Formula 8 or Formula 9.

  If the ΔTD ratio (END) does not reach −0.2% or more even if the cumulative number of times of the replenishment operation of (S5) reaches 3 times, in consideration of the unevenness of the TD ratio of the developer in the developing device 2 Also, there is no toner surely.

  In this case, without returning to (S5) again, it is determined that "toner is absent" (S12), the toner remaining amount confirmation sequence is ended, and the image formation restart is stopped (S13). Then, the display 300 displays "Please replace the toner bottle" (S14).

  In the present embodiment, it is determined that there is no toner in the toner bottle 7 under the condition that the ΔTD ratio (END) does not become −0.2% or more even if the replenishment operation in (S5) is performed three times. However, you may increase the number of times.

  As described above, the control unit 100 according to the present embodiment selectively executes at least the following three states based on the detection result acquired by the inductance sensor 26 after the start of execution of the toner remaining amount confirmation sequence. Specifically, the first state in which the image formation is immediately prohibited, the second state in which the image forming operation is permitted, and the third state in which the toner remaining amount confirmation sequence is executed again.

  In each of the above states, when the toner remaining amount confirmation sequence is started and it is possible to determine "with toner" or "without toner" in one replenishment operation, and "with toner" or in two or three replenishment operations. It is divided into cases where it is possible to determine "no toner".

  When the determination can be made by one replenishment operation (the first state and the second state), the toner remaining amount confirmation sequence can be completed in a short time, and the downtime can be reduced.

  On the other hand, in the case where the determination is made by performing the replenishment operation twice or three times (third state), the accuracy of the "toner-less" determination can be increased. In this case, it is possible to reduce the stress on the user in terms of the life of the toner bottle by preventing the determination of “no toner” in the state where the toner in the toner bottle is sufficient.

  By performing the control as described above, it is possible to suppress the decrease in the accuracy of the toner remaining amount determination while shortening the down time by the toner remaining amount checking sequence as much as possible.

Second Embodiment
The configuration of the second embodiment will be described. The description of the same configuration as that of the above-described embodiment will be omitted.

  In the first embodiment, if ΔTD ratio (END) ≧ −0.2%, “toner is present”. The value of -0.2% is taken as the "toner judgment value". Here, if the "toner presence judgment value" is lowered, for example, if it is lowered from -0.2% to -1.0%, the toner remaining amount confirmation sequence starts and "toner existence" is performed in one replenishment operation. The frequency of becoming However, depending on the unevenness in the TD ratio of the developer in the developing device 2, there may be a case in which it is determined that "toner is present" by mistake.

  The following is an example of the problem in the case where it is determined that "Toner is present" by mistake. That is, when the TD ratio decreases before the toner remaining amount confirmation sequence is performed again, the carrier adheres to the photosensitive drum. For this reason, there is a problem that an image of a portion of the attached carrier is whitened out. Since this problem hardly occurs when the TD ratio is high, it is preferable to set the target TD ratio: TD (target) high.

  In the present embodiment, the control unit changes the target TD ratio: TD (target) according to the density of the patch image Q. In particular, it is changed according to the durability of the developer in the developing device 2. Then, by changing the TD ratio of the developer so as to keep the density of the patch image Q constant, the change of the toner charge amount of the developer is suppressed, and the image density is stabilized. In addition, an upper limit value is set to the target TD ratio: TD (target). In addition, a lower limit value is set for the target TD ratio: TD (target) so that carrier adhesion does not occur.

  As described above, in the second embodiment, the threshold value as the “toner presence determination value” is changed according to the value of the target TD ratio: TD (target) determined according to the density of the patch image Q.

  FIG. 9 is a diagram showing the relationship between the target TD ratio and the toner presence determination value in the second embodiment. Specifically, the relationship between the target TD ratio: TD (target) and the “determination value with toner” is shown. The relationship of FIG. 9 is stored in advance in the ROM 102. The “toner presence determination value” may be set to another value as long as it is a numerical value larger than −0.9% as described in the first embodiment.

Third Embodiment
The configuration of the third embodiment will be described. The description of the same configuration as that of the above-described embodiment will be omitted.

  In the first embodiment, if ΔTD ratio (END) ≦ −0.9%, “no toner” is set. The value of -0.9% is taken as the "toner absence judgment value". In the determination of the flowchart (S15) of FIG. 6 of the first embodiment, the same applies to the case where the replenishment operation of repetition (S5) is performed.

  Even when unevenness occurs in the TD ratio of the developer in the developing device 2 after outputting an image having a high image ratio, as shown in FIG. 4, the unevenness decreases with time. From this, when the replenishment operation of repetition (S5) is performed, even if the threshold value as the "toner absence judgment value" is increased, for example, even if it is raised from -0.9% to -0.2% side, The possibility of making a mistake in the determination of "no toner" is reduced.

  For this reason, in the third embodiment, the control unit increases the "toner absence determination value" when the replenishment operation (S5) is repeatedly performed. This increases the possibility that it can be determined that "toner is absent" in the second replenishment operation. Then, the time of the toner remaining amount confirmation sequence can be shortened.

  In the third embodiment, the "no toner determination value" is changed from -0.9% to -0.7% when the replenishment operation (S5) is repeatedly performed according to the determination of the flowchart (S15) in FIG. It changed, but it does not matter if it is another numerical value. However, it is necessary to keep the relationship of “toner judgment value”> “toner judgment value”.

Fourth Embodiment
The configuration of the fourth embodiment will be described. The description of the same configuration as that of the above-described embodiment will be omitted.

  In the first embodiment, based on the determination of the flow chart (S15) of FIG. 6, the replenishment condition when the replenishment operation (S5) is repeatedly performed is the same as the first replenishment condition (10 revolutions of the replenishment motor 73). did.

  However, if the ΔTD ratio (END) is close to −0.2% (eg, −0.3%), if the replenishment motor 73 is driven 10 revolutions in the repetitive (S5) replenishment operation, the amount of replenishment toner is large. There is a possibility that it is too much. In this case, the target TD ratio: TD (target) may be greatly exceeded. Then, if the target TD ratio: TD (target) is largely exceeded, there is a risk of toner scattering, a fogging image of a white area, or the like.

  Therefore, in the fourth embodiment, the control unit changes the number of replenishment rotations: M of the replenishment motor 73 according to the previous value of the ΔTD ratio (END).

  FIG. 10 is a view showing a flowchart of the fourth embodiment. The basic flow is the same as FIG. 6 of the flowchart of the first embodiment, but in the fourth embodiment, the flows of (S16) and (S17) are added.

  When it is determined to repeatedly perform the replenishment operation in (S15), the number of replenishment rotations of the replenishment motor 73: M is determined based on the value of the ΔTD ratio (END) (S16). The relationship between the ΔTD ratio (END) and the number of replenishment rotations: M of the replenishment motor 73 used in (S16) is recorded in advance in the ROM 102. FIG. 11 is a chart of the relationship between the ΔTD ratio (END) of the fourth embodiment and the number of times of driving of the replenishment motor.

  From the relationship of FIG. 11, the number of times of replenishment rotation of the replenishment motor 73: M is determined, and the flow moves to (S17) to implement the replenishment operation. In FIG. 11, when ΔTD ratio (END) is −0.9% or more and less than −0.6%, M is set to 10, and when ΔTD ratio (END) is −0.6% or more to less than 0.4%, M = Although it is set as 8 and it is set as M = 6 at the time of -0.4% or more and less than -0.2%, it does not restrict to this.

IP: Image formation unit 1: Photosensitive drum 2. Photo development unit 7: Toner bottle 12: Scanner unit 26: Inductance sensor 27: Development drive motor 73: Supply motor 100: Control unit 101: CPU
102 ... ROM
103 ... RAM
232 ... Development sleeve

Claims (20)

An image forming apparatus capable of executing an image forming operation for forming an image on a recording material, comprising:
An image carrier,
In order to develop an electrostatic latent image formed on the image carrier, a developer container containing a developer containing toner and a carrier, a developer transport unit for transporting the developer contained in the developer container, and A developer carrying body for carrying the developer on the
The developing device is provided, detects the magnetic permeability of the developer contained in the developing container, and detects a toner concentration as a ratio of toner to carrier of the developer contained in the developing container Permeability sensor, and
A toner container provided so as to be mountable to a mounting portion of the image forming apparatus and containing the toner to be supplied to the developing container;
A drive motor rotationally driven to supply the toner contained in the toner container to the developing container;
A first detection toner concentration, which is the toner concentration of the developer stored in the developer container detected by the magnetic permeability sensor while the image forming operation is being performed, and the toner container should be stored in the developer container A first operation for driving the drive motor to rotate by the number of rotations based on a target toner concentration which is the target toner concentration of the developer and information on an image ratio of an image formed on the recording material; A control unit capable of executing a second operation of rotationally driving the drive motor by a predetermined number of rotations in a state in which the forming operation is interrupted;
Equipped with
The control unit may include a predetermined value that the first detected toner concentration is lower than the target toner concentration, and an absolute value of a difference between the first detected toner concentration and the target toner concentration is higher than a predetermined threshold. When the condition is satisfied, the image forming operation is interrupted to execute the second operation,
The control unit causes the drive motor to rotate for the predetermined number of rotations by performing the second operation one time each time the second operation is performed, and then interrupts the image forming operation. Resuming the image forming operation being interrupted based on the second detected toner concentration which is the toner concentration of the developer contained in the developer container detected by the magnetic permeability sensor while the image forming apparatus is running. An image forming apparatus characterized by selecting one from among a plurality of methods including: transferring the image forming apparatus to a possible state; and prompting replacement of the toner container attached to the attaching unit. The control unit rotationally drives the drive motor by the predetermined number of rotations by performing the second operation once each time the second operation is performed.
When the second detected toner density is higher than the target toner density, the state shifts to a state where it is possible to restart the interrupted image forming operation,
The image forming operation being interrupted when the second detected toner density is lower than the target toner density and the absolute value of the difference between the second detected toner density and the target toner density is lower than a first threshold Transition to a state where it is possible to resume
When the second detected toner density is lower than the target toner density, and the absolute value of the difference between the second detected toner density and the target toner density is higher than a second threshold higher than the first threshold, The image forming apparatus according to claim 1, wherein replacement of the toner container mounted in the mounting unit is promoted. The control unit rotates the drive motor for the predetermined number of rotations by one execution of the second operation each time the second operation is performed once, and then causes the second detected toner density to be set. Transitioning to a state where it is possible to restart the interrupted image forming operation, prompting replacement of the toner container mounted on the mounting unit, and repeating the second operation once. The image forming apparatus according to claim 1, wherein one of the plurality is selected and executed including execution. The control unit rotationally drives the drive motor by the predetermined number of rotations by performing the second operation once each time the second operation is performed.
When the second detected toner density is higher than the target toner density, the state shifts to a state where it is possible to restart the interrupted image forming operation,
The image forming operation being interrupted when the second detected toner density is lower than the target toner density and the absolute value of the difference between the second detected toner density and the target toner density is lower than a first threshold Transition to a state where it is possible to resume
When the second detected toner density is lower than the target toner density, and the absolute value of the difference between the second detected toner density and the target toner density is higher than a second threshold higher than the first threshold, Prompt replacement of the toner container mounted in the mounting portion,
When the second detected toner density is lower than the target toner density, and the absolute value of the difference between the second detected toner density and the target toner density is higher than the first threshold and lower than the second threshold, The image forming apparatus according to claim 3, wherein the second operation is repeatedly performed once. The control unit rotationally drives the drive motor by the predetermined number of rotations by performing the second operation once each time the second operation is performed.
The second detected toner density is lower than the target toner density, the absolute value of the difference between the second detected toner density and the target toner density is higher than the first threshold and lower than the second threshold, and If the second operation is not repeatedly performed a predetermined number of times, the second operation is repeatedly performed once,
The second detected toner density is lower than the target toner density, the absolute value of the difference between the second detected toner density and the target toner density is higher than the first threshold and lower than the second threshold, and 5. The image forming apparatus according to claim 4, wherein when the second operation is repeatedly performed for the predetermined number of times, replacement of the toner container attached to the attachment unit is promoted. The image forming apparatus according to claim 4, wherein the control unit is capable of changing the second threshold according to the number of times the second operation is repeatedly performed. The control unit is capable of changing the predetermined number of rotations for driving the drive motor in accordance with the second detected toner density when the second operation is repeatedly performed once. 7. An image forming apparatus according to any one of items 3 to 6. 8. The control unit, when urging replacement of the toner container mounted on the mounting unit, shifts to a state of limiting restart of the image forming operation being interrupted. The image forming apparatus according to any one of the above. The magnetic permeability sensor is accommodated in the developer container each time an image forming operation for forming an image on one sheet of recording material is performed in a continuous image forming operation for continuously forming images on a plurality of sheets of recording material. Detecting the magnetic permeability of the developer to detect the toner concentration of the developer contained in the developer container;
The control unit is configured to cause the first detected toner concentration to be lower than the target toner concentration in the continuous image forming operation, and an absolute value of a difference between the first detected toner concentration and the target toner concentration is greater than the predetermined threshold. The image forming apparatus according to any one of claims 1 to 8, wherein when the predetermined number of sheets is continuously satisfied, the second operation is performed. The image forming apparatus further includes an image density sensor for detecting the density of a toner image formed by developing the electrostatic latent image formed on the image carrier with the developer.
The image forming apparatus according to any one of claims 1 to 9, wherein the control unit is capable of changing the target toner density in accordance with the density of the toner image detected by the image density sensor. apparatus. An image forming apparatus capable of executing an image forming operation for forming an image on a recording material, comprising:
An image carrier,
In order to develop an electrostatic latent image formed on the image carrier, a developer container containing a developer containing toner and a carrier, a developer transport unit for transporting the developer contained in the developer container, and A developer carrying body for carrying the developer on the
The developing device is provided, detects the magnetic permeability of the developer contained in the developing container, and detects a toner concentration as a ratio of toner to carrier of the developer contained in the developing container Permeability sensor, and
A toner container provided so as to be mountable to a mounting portion of the image forming apparatus and containing the toner to be supplied to the developing container;
A drive motor rotationally driven to supply the toner contained in the toner container to the developing container;
A first detection toner concentration, which is the toner concentration of the developer stored in the developer container detected by the magnetic permeability sensor while the image forming operation is being performed, and the toner container should be stored in the developer container A first operation of rotationally driving the drive motor for a time based on a target toner concentration which is the target toner concentration of the developer and information on an image ratio of an image formed on the recording material; A control unit capable of executing a second operation of rotationally driving the drive motor for a predetermined period of time while the operation is suspended;
Equipped with
The control unit may include a predetermined value that the first detected toner concentration is lower than the target toner concentration, and an absolute value of a difference between the first detected toner concentration and the target toner concentration is higher than a predetermined threshold. When the condition is satisfied, the image forming operation is interrupted to execute the second operation,
The control unit rotates the drive motor for only the predetermined time by executing the second operation each time the second operation is performed, and then interrupts the image forming operation. Resuming the interrupted image forming operation based on the second detected toner concentration which is the toner concentration of the developer stored in the developer container detected by the magnetic permeability sensor during the An image forming apparatus characterized by selecting one of a plurality of methods including transitioning to a possible state and prompting replacement of the toner container mounted in the mounting portion. The control unit rotates and drives the drive motor for the predetermined time by executing the second operation each time the second operation is performed.
When the second detected toner density is higher than the target toner density, the state shifts to a state where it is possible to restart the interrupted image forming operation,
The image forming operation being interrupted when the second detected toner density is lower than the target toner density and the absolute value of the difference between the second detected toner density and the target toner density is lower than a first threshold Transition to a state where it is possible to resume
When the second detected toner density is lower than the target toner density, and the absolute value of the difference between the second detected toner density and the target toner density is higher than a second threshold higher than the first threshold, The image forming apparatus according to claim 11, wherein replacement of the toner container attached to the attachment unit is promoted. The control unit rotates the drive motor for only the predetermined time by executing the second operation each time the second operation is performed, and then, based on the second detected toner density. Transitioning to a state where it is possible to resume the interrupted image forming operation, prompting the user to replace the toner container mounted in the mounting unit, and repeating the second operation and executing it once. The image forming apparatus according to claim 11, wherein one of a plurality of operations is selected and executed.
The control unit rotates and drives the drive motor for the predetermined time by executing the second operation each time the second operation is performed.
When the second detected toner density is higher than the target toner density, the state shifts to a state where it is possible to restart the interrupted image forming operation,
The image forming operation being interrupted when the second detected toner density is lower than the target toner density and the absolute value of the difference between the second detected toner density and the target toner density is lower than a first threshold Transition to a state where it is possible to resume
When the second detected toner density is lower than the target toner density, and the absolute value of the difference between the second detected toner density and the target toner density is higher than a second threshold higher than the first threshold, Prompt replacement of the toner container mounted in the mounting portion,
When the second detected toner density is lower than the target toner density, and the absolute value of the difference between the second detected toner density and the target toner density is higher than the first threshold and lower than the second threshold, The image forming apparatus according to claim 13, wherein the second operation is repeatedly performed once. The control unit rotates and drives the drive motor for the predetermined time by executing the second operation each time the second operation is performed.
The second detected toner density is lower than the target toner density, the absolute value of the difference between the second detected toner density and the target toner density is higher than the first threshold and lower than the second threshold, and If the second operation is not repeatedly performed a predetermined number of times, the second operation is repeatedly performed once,
The second detected toner density is lower than the target toner density, the absolute value of the difference between the second detected toner density and the target toner density is higher than the first threshold and lower than the second threshold, and The image forming apparatus according to claim 14, wherein when the second operation is repeatedly performed for the predetermined number of times, replacement of the toner container attached to the attachment unit is prompted. The image forming apparatus according to claim 14, wherein the control unit can change the second threshold in accordance with the number of times the second operation is repeatedly performed. The control unit is capable of changing the predetermined time for driving the drive motor to rotate according to the second detected toner concentration when the second operation is repeatedly performed once. The image forming apparatus according to any one of 13 to 16. 18. The image forming apparatus according to claim 17, wherein the control unit shifts to a state of restricting resuming the image forming operation being interrupted when urging the user to replace the toner container attached to the attachment unit. The image forming apparatus according to any one of the above. The magnetic permeability sensor is accommodated in the developer container each time an image forming operation for forming an image on one sheet of recording material is performed in a continuous image forming operation for continuously forming images on a plurality of sheets of recording material. Detecting the magnetic permeability of the developer to detect the toner concentration of the developer contained in the developer container;
The control unit is configured to cause the first detected toner concentration to be lower than the target toner concentration in the continuous image forming operation, and an absolute value of a difference between the first detected toner concentration and the target toner concentration is greater than the predetermined threshold. The image forming apparatus according to any one of claims 11 to 18, wherein when the predetermined number of sheets is continuously satisfied, the second operation is performed. The image forming apparatus further includes an image density sensor for detecting the density of a toner image formed by developing the electrostatic latent image formed on the image carrier with the developer.
The image forming apparatus according to any one of claims 11 to 19, wherein the control unit is capable of changing the target toner density in accordance with the density of the toner image detected by the image density sensor. apparatus.

Images