JP2014059416A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of determining whether a developing unit is full of toner or abnormality occurs to detection means.SOLUTION: An image forming apparatus of the present invention includes a developing unit, a first detection unit, and a determination unit. The developing unit develops an electrostatic latent image formed on a developer carrier with toner. The first detection unit detects the amount of toner in the developing unit. The determination unit determines whether abnormality occurs to the first detection unit or the developing unit is full of toner, on the basis of values indicating variations of the amount of toner detected by the first detection unit in each of a plurality of sampling timings within a predetermined period.

Description

  The present invention relates to an image forming apparatus.

  In an electrophotographic image forming apparatus, a configuration is used in which toner is supplied from a toner container to a developing unit. When toner is replenished, the toner that is replenished from the toner container (replenishment toner) and the toner inside the development unit differ in the toner deterioration state, so the development system becomes unstable immediately after replenishment (as for the quality of the background Dirt (ground fog), concentration fluctuation, etc.). Therefore, in order to stabilize the development system as much as possible, the amount of toner in the development unit is detected with high accuracy, and if the amount falls below the predetermined amount, the toner is replenished, so that the ratio between the toner immediately after replenishment and the replenished toner is constant. The replenishment amount is controlled so that As a technique for detecting the toner amount, a technique using an optical detection means provided in the developing unit is known.

  For example, Patent Document 1 discloses an optical toner detection unit capable of detecting the amount of toner in the developing unit at at least two levels for the purpose of detecting and controlling the amount of toner in the developing unit with higher accuracy. A control means for detecting the toner amount in the configuration having the above is disclosed. Patent Document 2 discloses a technique for changing a light emission intensity of an optical light emitting unit provided in a developing unit or a light receiving sensitivity of a light receiving unit, or a threshold value for binarizing a detection signal of the light receiving unit. ing.

  However, the techniques disclosed in Patent Document 1 and Patent Document 2 have a problem that it is impossible to determine whether the toner in the developing unit is full or whether the detection unit is abnormal.

  If there is an abnormality in the detection means, the toner in the development unit may be empty, so printing must be stopped immediately, but the toner in the development unit is full. If so, printing can be continued by supplying toner. That is, since it is impossible to determine whether the toner in the developing unit is full or whether the detection unit is abnormal, there is a problem that the image forming apparatus cannot be operated properly.

  The present invention has been made in view of the above, and provides an image forming apparatus capable of determining whether the toner in the developing unit is full or whether a detection unit has an abnormality. Objective.

  In order to solve the above-described problems and achieve the object, the present invention provides a developing unit that develops an electrostatic latent image formed on an image carrier with toner, and a first that detects the amount of toner in the developing unit. The amount of toner detected by the detection unit and the first detection unit at a plurality of sampling timings within a predetermined period exceeds a first threshold, and is detected by the first detection unit at each sampling timing. The image forming apparatus includes a determination unit that determines that an abnormality has occurred in the first detection unit when the value indicating the variation in the toner amount is equal to or less than a second threshold value.

  According to the present invention, it can be determined whether the toner in the developing unit is full or whether an abnormality has occurred in the detection means.

FIG. 1 is a mechanical configuration diagram illustrating an example of an image forming apparatus. FIG. 2 is a diagram illustrating a hardware configuration example of the image forming apparatus. FIG. 3 is a diagram illustrating an example of a mechanical configuration of the developing unit. FIG. 4 is a diagram illustrating an example of a mechanical configuration of the developing unit. FIG. 5 is a diagram illustrating an example of the waveform of the output voltage of the light receiving element. FIG. 6 is a diagram illustrating an example of the waveform of the output voltage of the light receiving element. FIG. 7 is a diagram illustrating an example of the waveform of the output voltage of the light receiving element. FIG. 8 is a diagram illustrating a functional configuration example of the image forming apparatus according to the first embodiment. FIG. 9 is a diagram illustrating waveforms of output voltage values of the light receiving element when the first detection unit is abnormal and when the toner is full in the developing unit. FIG. 10 is a diagram illustrating the waveform of the output voltage value of the light receiving element when the toner in the developing unit is low. FIG. 11 is a flowchart illustrating an operation example of the image forming apparatus according to the first embodiment. FIG. 12 is a flowchart illustrating an operation example of the image forming apparatus according to the second embodiment. FIG. 13 is a diagram illustrating a functional configuration example of the image forming apparatus according to the third embodiment. FIG. 14 is a flowchart illustrating an operation example of the image forming apparatus according to the third embodiment. FIG. 15 is a diagram illustrating a functional configuration example of the image forming apparatus according to the fourth embodiment. FIG. 16 is a flowchart illustrating an operation example of the image forming apparatus according to the fourth embodiment. FIG. 17 is a diagram illustrating a functional configuration example of the image forming apparatus according to the fifth embodiment. FIG. 18 is a flowchart illustrating an operation example of the image forming apparatus according to the fifth embodiment.

  Hereinafter, embodiments of the image forming apparatus of the present invention will be described in detail with reference to the accompanying drawings. The image forming apparatus of the present invention can be applied to any apparatus that forms an image by electrophotography, and can be applied to, for example, an electrophotographic image forming apparatus or a multifunction peripheral (MFP). Note that a multifunction peripheral is a device having at least two functions of a printing function, a copying function, a scanner function, and a facsimile function.

(First embodiment)
FIG. 1 is a mechanical configuration diagram illustrating an example of an image forming apparatus 1 according to the present embodiment. As shown in FIG. 1, in the image forming apparatus 1, image forming units 2A, 2B, 2C, and 2D for respective colors and toner containers 22A, 22B, 22C, and 22D are arranged side by side along the transfer belt 12. .

  The transfer belt 12 is an endless belt wound around a secondary transfer drive roller 3 and a transfer belt tension roller 4 that are rotationally driven. The toner density sensor 70 is a sensor for detecting the density of toner transferred onto the transfer belt 12 (the density of a toner image to be described later), and corresponds to the amount of light reflected on the transfer belt 12. Output the signal.

  The image forming unit (image forming unit) 2A includes a photoconductor 5A, a charger 6A disposed around the photoconductor 5A, an exposure unit 7, a developing unit 8A, and a cleaning blade 9A. Yes. The plurality of image forming units 2A, 2B, 2C, and 2D have the same internal configuration except that the color of the toner image to be formed is different.

  The exposure unit 7 is configured to irradiate laser beams 10A, 10B, 10C, and 10D that are exposure lights corresponding to image colors formed by the image forming units 2A, 2B, 2C, and 2D. Further, the image forming apparatus 1 is formed on a paper feed tray 14 for stacking paper 15, a paper feed roller 16 for conveying the paper 15, a registration roller 17, a paper discharge roller 19, a double-sided roller 20, and a transfer belt 12. A secondary transfer roller 13 for transferring the image (toner image) to the paper, and a fixing device 18 for fixing the toner to the paper 15 to which the toner has been transferred. A paper discharge sensor 21 that detects that the paper 15 has passed is close to the paper discharge roller 19. Further, an image adjustment pattern (patch image) formed on the transfer belt 12 and a waste toner box 23 for collecting toner remaining without being transferred to the paper 15 are arranged.

  Next, a general operation in the image forming apparatus 1 configured as described above will be described. When forming an image, the outer peripheral surface of the photoconductor 5A is uniformly charged by the charger 6A in the dark, and then exposed by the emitted light (LED light or laser light) 10A from the exposure device 7 to form an electrostatic latent image. Is formed. The developing unit 8A visualizes (develops) the electrostatic latent image with toner, whereby a toner image is formed on the photoreceptor 5A. This toner image is transferred onto the transfer belt 12 by the action of the primary transfer roller 11A at a position (primary transfer position) where the photoreceptor 5A and the transfer belt 12 are in contact with each other. By this transfer, a toner image is formed on the transfer belt 12. After the toner image has been transferred, the photoreceptor 5A waits for the next image formation after the unnecessary toner remaining on the outer peripheral surface is wiped off by the cleaning blade 9A.

  As described above, the transfer belt 12 to which the toner image is transferred by the image forming unit 2A is conveyed to the next image forming unit 2B. In the image forming unit 2B, a toner image of a color corresponding to the image forming unit 2B is formed on the photoconductor 5B by a process similar to the image forming process in the image forming unit 2A, and the toner formed on the photoconductor 5B. The image is superimposed and transferred onto the toner image (toner image transferred by the image forming unit 2A) formed on the transfer belt 12. The transfer belt 12 is further conveyed to the next image forming units 2C and 2D, and the toner image formed on the photoconductor 5C by the image forming unit 2C and the image forming unit 2D on the photoconductor 5D by the same operation. Each of the formed toner images is sequentially superimposed on the transfer belt 12 and transferred. Thus, a full-color image is formed on the transfer belt 12. The transfer belt 12 on which the full-color superimposed image is formed is conveyed to the position of the secondary transfer roller 13. Further, the density of the toner image formed on the transfer belt 12 can be detected by a toner density sensor 70 installed further downstream than the primary transfer roller 11D.

  During the paper transport operation during image formation, the paper 15 stored in the paper feed tray 14 is sequentially sent out by rotating the paper feed roller 16 clockwise from the top. The driving of the registration roller 17 is started at a timing such that the position of the toner image and the paper 15 overlaps on the toner image conveyed by the transfer belt 12 and the secondary transfer roller 13. At this time, the registration roller 17 is rotated counterclockwise to feed out the paper 15. The paper 15 sent out by the registration roller 17 transfers the toner image on the transfer belt 12 to the paper 15 by the secondary transfer roller 13, and then the toner image is fixed by heat and pressure by the fixing device 18. The paper is discharged out of the image forming apparatus 1 by a paper discharge roller 19 that is driven to rotate counterclockwise.

  When performing duplex printing, the paper discharge roller 19 is driven to rotate clockwise before the paper 15 passes through the paper discharge roller 19, and the paper 15 is conveyed to the double-sided conveyance path. The sheet 15 conveyed to the duplex conveyance path is conveyed again to the registration roller 17 via the duplex roller 20. The sheet 15 that has reached the registration roller 17 is again fed from the registration roller 17, and after the toner image is transferred to the opposite side of the sheet surface by the secondary transfer roller 13, the toner image is The sheet is fixed by pressure and discharged to the outside of the image forming apparatus 1 by a discharge roller 19 that is driven to rotate counterclockwise.

  Each of the developing units 8A, 8B, 8C, and 8D is provided with a sensor that detects whether or not the toner in the developing unit has reached a certain amount (a detailed example will be described later). And the toner is supplied from the toner containers 22A, 22B, 22C, and 22D to the developing units 8A, 8B, 8C, and 8D. In this example, the toner container 22A is configured to be removable from the developing unit 8A, the toner container 22B is configured to be removable from the developing unit 8B, and the toner container 22C is configured to be removable from the developing unit 8C. The toner container 22D is configured to be detachable from the developing unit 8D. Hereinafter, when the developing units 8A, 8B, 8C, and 8D are not distinguished from each other, they are simply referred to as the developing unit 8, and when the toner containers 22A, 22B, 22C, and 22D are not distinguished from each other, they are simply referred to as the toner container 22. is there.

  FIG. 2 is a diagram illustrating a hardware configuration example of the image forming apparatus 1. As shown in FIG. 2, the image forming apparatus 1 includes an external I / F 24, a CPU 25, a ROM 26, a RAM 27, an operation panel I / F 28, an operation panel 29, an NVRAM (K) 31, and an NVRAM (C ) 32, NVRAM (M) 33, NVRAM (Y) 34, I / O 35, toner supply motor 36, toner supply clutch (K) 37, toner supply clutch (C) 38, and toner supply clutch (M) 39, a toner supply clutch (Y) 40, a developing unit toner detection sensor (K) 41, a developing unit toner detection sensor (C) 42, a developing unit toner detection sensor (M) 43, and a developing unit. A toner detection sensor (Y) 44, an image processing IC 45, and a controller 46 are provided, and these are connected to each other via a system bus 30.

  The CPU 25 generally controls access to various devices connected to the system bus 36 based on a control program or the like stored in the ROM 26, and includes sensors, motors, clutches, heaters, etc. connected via the I / O 35. Control input / output of electrical components.

  The ROM 26 is a non-volatile memory that stores a control program of the CPU 25 and the like.

  The RAM 27 is a volatile memory that functions as a main memory, work area, and the like for the CPU 25, and is used for a recording data expansion area, an environment data storage area, and the like.

  Each NVRAM 31, 32, 33, 34 is mounted in each toner container 22A, 22B, 22C, 22D, and stores information such as the remaining amount of each toner container 22.

  A printer mode or the like can be set by an operation input to the operation panel 29 connected via the operation panel I / F 28.

  By driving the toner supply motor 36 and turning on the toner supply clutches 37, 38, 39, and 40, the toner of each color from each toner container 22 is supplied to each developing unit 8.

  In each developing unit 8, developing unit toner detection sensors 41, 42, 43, 44 are installed in order to detect whether or not a certain amount of toner is contained.

  The image processing IC 45 receives the image data from the controller 46 and controls exposure by the exposure unit 7 according to the image data. Further, the image processing IC 45 has a function of calculating the toner consumption amount per page from the image data received from the controller 46 and notifying the CPU 25 via the system bus 30 of the calculated toner consumption amount.

  FIG. 3 is a diagram illustrating an example of a mechanical configuration of the developing unit 8A. The configurations of the other developing units 8B, 8C, and 8D are the same. As shown in FIG. 3, the developing unit 8 </ b> A includes a developing unit toner detection sensor 41 and a supply roller 49. The toner stored in the developing unit 8A is laminated on the surface of the supply roller 49, and the electrostatic latent image on the photoreceptor 5A is visible using the toner on the surface of the supply roller 49 in the development process. Image.

  The developing unit toner detection sensor 41 is a sensor for detecting the toner amount in the developing unit 8A, and outputs a signal corresponding to the toner amount in the developing unit 8A. More specifically, the developing unit toner detection sensor 41 includes a light emitting element 47 and a light receiving element 48, and the light emitting element 47 and the light receiving element 48 are attached inside the developing unit 8A. The light emitted from the light emitting element 47 passes through the inside of the developing unit 8A and is received by the light receiving element 48. As shown in FIG. 3, when the amount of toner in the developing unit 8A is small and no toner is present on the optical path, light is transmitted, and the light emitted from the light emitting element 47 is supplied to the light receiving element 48 as it is. . On the other hand, as shown in FIG. 4, the amount of toner in the developing unit 8A is large, and light is blocked when toner is present on the optical path. Less. In the present embodiment, the light receiving element 48 outputs a voltage signal corresponding to the amount of received light. In this example, the output value of the voltage signal is set to increase as the amount of received light decreases (that is, the output value of the voltage signal increases as the amount of toner in the developing unit increases). is not. In other words, the voltage signal output from the light receiving element 48 can be regarded as indicating the amount of toner in the developing unit 8A. In this example, the developing unit toner detection sensor 41 corresponds to a “first detection unit” in the claims.

  Further, the toner in the developing unit 8A is constantly stirred by a stirring paddle (not shown) for the purpose of uniformizing the density of the deteriorated toner and the new toner. When the toner amount is small, the waveform of the voltage value output from the light receiving element 48 is as shown by 50A illustrated in FIG. On the other hand, when the amount of toner in the developing unit 8A is large, the waveform of the voltage value output from the light receiving element 48 is as indicated by 50B illustrated in FIG. In the prior art, a threshold value 51 is provided for the output voltage value, the presence / absence of toner is detected in the sampling period, and the toner amount is determined from the ratio of the number of detections. Here, in order to stabilize the developing system as much as possible, as soon as the amount of toner in the developing unit 8 falls below a predetermined amount, a predetermined amount of replenishing toner is replenished, so that the ratio between the toner immediately after replenishment and the replenishing toner is constant. You are in control. In this embodiment, sampling is performed 50 times at a sampling period of 10 ms at the time of toner amount detection, and when no toner is detected 40 times or more, it is determined that the toner amount in the developing unit has decreased, and toner replenishment is started.

  FIG. 7 is a diagram illustrating sensor waveforms when the developing unit toner detection sensor 41 is abnormal and when the toner is full in the developing unit 8A. When the light emitting element 47 and the light receiving element 48 in the developing unit 8A fail, when the connector is poorly connected, or when an abnormality occurs in the developing unit toner detection sensor 41, such as an optical path shift, the light does not enter the light receiving element 48. 50C is always in a state with toner. On the other hand, when the toner is full in the developing unit 8A and the draft surface of the toner is positioned higher than the optical path of the light emitting element 47 and the light receiving element 48, the sensor waveform 50D is slightly changed, The threshold value 51 or less is never reached, and the toner is always present, as in the case where the developing unit toner detection sensor 41 is abnormal.

  Here, conventionally, it is impossible to determine whether the developing unit toner detection sensor 41 is abnormal or whether the developing unit 8A is full of toner. Therefore, even when printing can be continued, printing must be stopped, and the image forming apparatus cannot be operated appropriately. Therefore, in the present embodiment, an abnormality is detected in the developing unit toner detection sensor 41 based on a value indicating a variation in the output voltage of the developing unit toner detection sensor 41 (which can be regarded as the amount of toner in the developing unit 8A). It is determined whether the toner is full in the developing unit 8A. This will be specifically described below.

  FIG. 8 is a block diagram illustrating a functional configuration example of the image forming apparatus 1. As illustrated in FIG. 8, the image forming apparatus 1 includes a first detection unit 101, a determination unit 102, a first control unit 103, a second control unit 104, and a toner supply unit 105. The first detection unit 101 has a function of detecting the toner amount in the developing unit 8. In this example, the first detection unit 101 is realized by the above-described developing unit toner detection sensors (41, 42, 43, 44).

  The determination unit 102 generates an abnormality in the first detection unit 101 based on a value indicating the variation in the toner amount detected by the first detection unit 101 at each of a plurality of sampling timings within a predetermined period. It is determined whether the toner in the developing unit 8 is full. In the present embodiment, the determination unit 102 determines that the toner amount detected by the first detection unit 101 at each sampling timing exceeds the first threshold value and the toner amount detected by the first detection unit 101 at each sampling timing. When the value indicating the variation is equal to or less than the second threshold value, it is determined that an abnormality has occurred in the first detection unit 101. On the other hand, the determination unit 102 indicates a variation in the toner amount detected by the first detection unit 101 at each sampling timing, and the toner amount detected by the first detection unit 101 at each sampling timing exceeds the first threshold value. When the value exceeds the second threshold value, it is determined that the toner is full in the developing unit 8.

More specifically, it is as follows. 9 shows the output voltage value of the light receiving element 48 when the first detection unit 101 is abnormal (when the development unit toner detection sensor is abnormal) and when the toner is full in the development unit 8 (in the first detection unit 101). FIG. 6 is a diagram illustrating a waveform of a detected toner amount). Hereinafter, a method for determining abnormality of the first detection unit 101 and toner fullness due to variations in the amount of toner detected by the first detection unit 101 (variations in the output voltage value of the light receiving element 48) will be described. In this example, the light receiving element 48 in the developing units 8A, 8B, 8C, and 8D is a device that can acquire voltages with a plurality of values. In this example, the reference voltage corresponding to the light emitted from the light emitting element 47 is set to 3.3V, and the toner amount can be detected as an analog value. The threshold value 51 with / without toner is 2.0V, When the toner amount is detected, sampling is performed 50 times at a sampling period of 10 ms. In this example, the threshold value 51 corresponds to the “first threshold value” in the claims, and a period during which sampling of a 10 ms cycle is performed 50 times (in the following description, may be referred to as “sampling period”) is “ It can be understood that it corresponds to a “predetermined period”. In this configuration, an example of a voltage value when the first detection unit 101 is abnormal is as shown in FIG. 9A-2, and an example of a toner full voltage value is shown in FIG. 9B-2. Become. Here, although the voltage value shows a substantially constant value when the first detection unit 101 is abnormal, it can be seen that there is a variation of about 0.5 V when the toner is full. In the present embodiment, a value (variance) indicating this variation is obtained by the following formula, and this value corresponds to a threshold value (a “second threshold value” in the claims). If it exceeds (Yes), it is determined that the toner is full.

  In this embodiment, the variation is obtained by the above equation. For example, the maximum value and the minimum value during sampling are held, and if this difference is within a certain value, it is determined that there is an abnormality in the first detection unit 101. Any method that can estimate the variation may be used.

  The determination unit 102 can also determine the presence or absence of toner in the developing unit 8 based on a value indicating the variation in the toner amount detected by the first detection unit 101 at each sampling timing. FIG. 10 is a diagram illustrating a waveform of the output voltage value (toner amount detected by the first detection unit 101) of the light receiving element 48 when the toner in the developing unit 8 is low. In this example, the light receiving element 48 in the developing units 8A, 8B, 8C, and 8D is a device that can acquire voltages with a plurality of values. In this example, the reference voltage corresponding to the light emitted from the light emitting element 47 is set to 3.3V, and the toner amount can be detected as an analog value. The threshold value 51 with / without toner is 2.0V, When the toner amount is detected, sampling is performed 50 times at a sampling period of 10 ms. In this configuration, examples of voltage values when the toner in the developing unit 8 is reduced are as shown in (a-2) and (b-2) of FIG. Here, when the toner in the developing unit 8 is empty, the voltage value is almost constant, but it can be seen that there is a variation of about 1 V when the toner is not empty but decreased. In the present embodiment, a value (variance) indicating this variation is obtained by the above formula, and this value is larger than a predetermined value, and the number of times that the output voltage value of the light receiving element 48 exceeds the threshold value 51 out of 50 sampling timings. Is greater than a predetermined number, it is determined that there is toner.

  Returning to FIG. 8 again, the description will be continued. The first control unit 103 performs control to stop the image forming operation (printing) when the determination unit 102 determines that an abnormality has occurred in the first detection unit 101. The second control unit 104 controls the operation of the agitation paddle described above. The toner supply unit 105 supplies toner from the toner container 22 to the developing unit 8.

  In the present embodiment, the functions of the determination unit 102, the first control unit 103, the second control unit 104, and the toner replenishment unit 105 described above are executed by the CPU 25 developing a program stored in the ROM 26 or the like on the RAM 27. It is realized by doing. For example, at least a part of the functions of the determination unit 102, the first control unit 103, the second control unit 104, and the toner supply unit 105 described above is realized by a dedicated hardware circuit. It may be a form.

  Next, an operation example of the image forming apparatus 1 will be described with reference to FIG. FIG. 11 is a flowchart illustrating an operation example of the image forming apparatus 1. First, the second control unit 104 agitates the toner in the developing unit 8 by performing control to rotate the agitation paddle (step S201). In this embodiment, the rotation speed of the stirring paddle is set to 145 mm / sec. Then, the first detection unit 101 starts detecting the toner amount (step S202). In the present embodiment, every time the sampling timing reaches every 10 ms, the light emitting element 47 emits light toward the light receiving element 48, and the light receiving element 48 outputs a voltage signal corresponding to the received light quantity. In this example, the voltage signal output from the light receiving element 48 is passed to the determination unit 102. After the sampling period has elapsed (after the number of sampling timings reaches 50), the determination unit 102 determines the number of times that no toner is detected among the 50 sampling timings (that is, the voltage value output from the light receiving element 48). It is determined whether or not (the number of times that is less than or equal to the threshold value 51) is a predetermined number or more (step S203). In the present embodiment, the predetermined number of times is set to 40, but is not limited to this.

  When it is determined that the number of times that no toner is detected is greater than or equal to the predetermined number (result of step S203: YES), the toner replenishing unit 105 replenishes the developing unit 8 with toner (step S204). On the other hand, if it is determined that the number of times that no toner has been detected is not equal to or greater than the predetermined number (the result of step S203: NO), the determination unit 102 determines whether there is always toner, that is, receives light at each sampling timing. It is determined whether or not the voltage value output from the element 48 exceeds the threshold value 51 (step S205).

  If it is determined that toner is not always present (result of step S205: NO), the process ends. On the other hand, when it is determined that the toner is always present (result of step S205: YES), the determination unit 102 determines whether or not the value indicating the variation in the toner amount exceeds the second threshold (step S206). In the present embodiment, the determination unit 102 determines whether or not the variance indicating the variation in the voltage value output from the light receiving element 48 at each sampling timing exceeds the second threshold value. When it is determined that the variance is equal to or smaller than the second threshold (result of step S206: NO), the determination unit 102 determines that an abnormality has occurred in the first detection unit 101, and the process is step. The process proceeds to S207. In step S207, the first control unit 103 performs control to stop printing. On the other hand, when it is determined that the variance indicating the variation in the voltage value output from the light receiving element 48 at each sampling timing exceeds the second threshold value (result of step S206: YES), the determination unit 102 In step S5, it is determined that the toner is full, and the process ends.

  In this embodiment, when it is determined that the toner is full, the toner replenishing operation is not performed, and printing can be continued without stopping unnecessary printing. On the other hand, if it is determined that there is an abnormality in the first detection unit 101, it cannot be determined how much toner actually remains in the developing unit 8, and there is a possibility that toner does not enter the developing unit 8. Because there is also, it stops printing immediately.

  As described above, in the present embodiment, an abnormality is detected in the first detection unit 101 based on the value (dispersion) indicating the variation in toner amount detected by the first detection unit 101 (developing unit toner detection sensor). Whether the toner has occurred or whether the toner in the developing unit 8 is full is determined. More specifically, the toner amount detected by the first detection unit 101 at each sampling timing exceeds the threshold value 51, and a value indicating the variation in the toner amount detected by the first detection unit 101 at each sampling timing is obtained. If it is less than or equal to the second threshold, it is determined that an abnormality has occurred in the first detection unit 101. On the other hand, the toner amount detected by the first detection unit 101 at each sampling timing exceeds the threshold value 51, and the value indicating the variation in the toner amount detected by the first detection unit 101 at each sampling timing exceeds the second threshold value. If it exceeds, it is determined that the toner in the developing unit 8 is full. According to the present embodiment, it is possible to accurately determine whether an abnormality has occurred in the first detection unit 101 or whether the toner in the developing unit 8 is full. Therefore, the image forming apparatus 1 can be appropriately operated. Can do.

(Second Embodiment)
Next, a second embodiment will be described. Description of parts common to the first embodiment described above will be omitted as appropriate. In the second embodiment, when the determination unit 102 determines that an abnormality has occurred in the first detection unit 101, the second control unit 104 has a function of performing control to increase the stirring speed by the stirring paddle. This is different from the first embodiment described above. Here, since the variation in the toner amount is detected while stirring the toner in the developing unit 8, the first detection unit is detected by detecting the toner amount again in a state where the variation is intentionally increased. The accuracy of determining whether or not an abnormality has occurred in 101 can be improved. In the second embodiment, by increasing the rotational speed of the stirring paddle, a state in which the variation in the toner amount becomes large is created.

  FIG. 12 is a flowchart illustrating an operation example of the image forming apparatus according to the second embodiment. The contents of steps S301 to S306 in FIG. 12 are the same as the contents of steps S201 to S206 in FIG. If it is determined in step S306 that the value indicating the variation in toner amount is equal to or less than the second threshold (result of step S306: NO), the second control unit 104 can increase the rotation speed of the stirring paddle. It is determined whether or not (step S307). If it is determined that the rotation speed of the stirring paddle cannot be increased (result of step S307: NO), the process proceeds to step S309. In step S309, the first control unit 103 performs control to stop printing.

  On the other hand, when it is determined that the rotational speed of the stirring paddle can be increased (result of step S307: YES), the second control unit 104 performs control to increase the rotational speed of the stirring paddle (step S308). ). In the present embodiment, the second control unit 104 sets the rotation speed of the stirring paddle motor so that the variation becomes the largest. More specifically, the second control unit 104 sets the rotation speed of the motor to an upper limit value (200 mm / sec in this example). After step S308, the process proceeds to step S301, and the processes after step S301 are repeated. If it is determined again that the value indicating the variation in the toner amount is equal to or smaller than the second threshold (result of step S306: NO), the result of step S307 is also negative and printing is stopped (step S309). ).

(Third embodiment)
Next, a third embodiment will be described. Description of parts common to the above-described embodiments will be omitted as appropriate. FIG. 13 is a diagram illustrating a functional configuration example of the image forming apparatus 100 according to the third embodiment. As illustrated in FIG. 13, the image forming apparatus 100 further includes a second detection unit 106 and a third control unit 107. The second detection unit 106 has a function of detecting the density of the toner image. In this example, the second detection unit 106 is realized by the toner density sensor 70 described above. When the determination unit 102 determines that an abnormality has occurred in the first detection unit 101 and the density of the toner image detected by the second detection unit 106 is normal, the third control unit 107 Control is performed to continue the image forming operation.

  FIG. 14 is a flowchart illustrating an operation example of the image forming apparatus 100. The contents of steps S401 to S406 in FIG. 14 are the same as the contents of steps S201 to S206 in FIG. In step S406, when it is determined that the value indicating the variation in toner amount is equal to or smaller than the second threshold value (result of step S406: NO), that is, the determination unit 102 has an abnormality in the first detection unit 101. If it is determined that there is a print request, the third control unit 107 checks whether there is a print request for the next page (step S407). If there is no next page print request (result of step S407: NO), the process proceeds to step S411. In step S411, the first control unit 103 performs control to stop printing.

  On the other hand, when there is a print request for the next page (result of step S407: YES), the second detection unit 106 detects the density of the toner image (step S408). Next, the third control unit 107 determines whether or not the density of the toner image detected by the second detection unit 106 is normal (step S409). When it is determined that the density of the toner image detected by the second detection unit 106 is normal (result of step S409: YES), the third control unit 107 performs control to continue printing (step S410). . Thereafter, the process proceeds to step S407, and the processes after step S407 are repeated, and printing is continued until the break of the print job (until there is no print request for the next page).

(Fourth embodiment)
Next, a fourth embodiment will be described. Description of parts common to the above-described embodiments will be omitted as appropriate. FIG. 15 is a diagram illustrating a functional configuration example of the image forming apparatus 200 according to the fourth embodiment. As shown in FIG. 15, the image forming apparatus 200 further includes a fourth control unit 108. The fourth control unit 108 performs control to forcibly discharge the toner in the developing unit 8 when the determining unit 102 determines that the toner is full in the developing unit 8.

  Here, when it is determined that the toner is full, it can be seen that a larger amount of toner is supplied than expected or the amount of toner consumption is less than expected. In either case, the ratio between the toner amount in the developing unit 8 and the replenished toner amount cannot be controlled as intended, and there is a concern about the deterioration of the image quality. By forcibly discharging the toner in the section 8, the toner amount in the developing section 8 is adjusted, and the image quality is stabilized.

  FIG. 16 is a flowchart illustrating an operation example of the image forming apparatus 200. The contents of steps S501 to S506 in FIG. 16 are the same as the contents of steps S201 to S206 in FIG. If it is determined in step S506 that the value indicating the variation in toner amount exceeds the second threshold (result of step S506: YES), that is, the determination unit 102 is full of toner in the developing unit 8. If it is determined, the fourth control unit 108 performs control to forcibly discharge the toner in the developing unit 8 (step S508). On the other hand, when it is determined that the value indicating the variation in the toner amount is equal to or smaller than the second threshold (result of step S506: NO), that is, the determination unit 102 has an abnormality in the first detection unit 101. If it is determined, the first control unit 103 performs control to stop printing (step S507).

(Fifth embodiment)
Next, a fifth embodiment will be described. Description of parts common to the above-described embodiments will be omitted as appropriate. FIG. 17 is a diagram illustrating a functional configuration example of the image forming apparatus 300 according to the fifth embodiment. As illustrated in FIG. 17, the image forming apparatus 300 further includes a second detection unit 106 and a fifth control unit 109.

  The second detection unit 106 has a function of detecting the density of the toner image. In this example, the second detection unit 106 is realized by the toner density sensor 70 described above. When the determination unit 102 determines that the toner in the developing unit 8 is full, the fifth control unit 109 adjusts the toner density based on the toner image density detected by the second detection unit 106. Perform control to be executed. Various known techniques can be used to adjust the toner density.

  Here, when it is determined that the toner is full, it can be seen that a larger amount of toner is supplied than expected or the amount of toner consumption is less than expected. In any case, the ratio between the toner amount in the developing unit 8 and the replenishment toner amount cannot be controlled as intended, and there is a concern that the image quality may be deteriorated. Therefore, in the present embodiment, the above-described toner density sensor 70 is used to check the occurrence of toner fading, and if the toner is fading, image density can be maintained by executing toner density adjustment.

  FIG. 18 is a flowchart illustrating an operation example of the image forming apparatus 300. The contents of steps S601 to S606 in FIG. 18 are the same as the contents of steps S201 to S206 in FIG. If it is determined in step S606 that the value indicating the variation in toner amount is equal to or smaller than the second threshold value (result of step S606: NO), the first control unit 103 performs control to stop printing (step S606). S607).

  On the other hand, if it is determined in step S606 that the value indicating the variation in the toner amount exceeds the second threshold value (result of step S606: YES), that is, the determination unit 102 is full of toner in the developing unit 8. When it is determined that the toner image density is NO, the second detection unit 106 detects the density of the toner image (step S608). Next, the fifth control unit 109 determines whether or not the density of the toner image detected by the second detection unit 106 is normal (step S609). When it is determined that the density of the toner image detected by the second detection unit 106 is not normal (result of step S609: NO), the fifth control unit 109 performs control to execute toner density adjustment (step S609). Step S610).

  As mentioned above, although embodiment of this invention was described, each above-mentioned embodiment was shown as an example and is not intending limiting the range of invention. The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above-described embodiments. For example, some components may be deleted from all the components shown in the embodiment.

  The program executed by the CPU 25 of the above-described embodiment is a file in an installable format or an executable format, and is a computer such as a CD-ROM, a flexible disk (FD), a CD-R, or a DVD (Digital Versatile Disk). You may comprise so that it may record and provide on a readable recording medium.

  Furthermore, the program executed by the CPU 25 of the above-described embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Further, the program executed by the CPU 25 of the above-described embodiment may be provided or distributed via a network such as the Internet.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image forming unit 5 Photoconductor 8 Developing part 12 Transfer belt 41 Developing part toner detection sensor 42 Developing part toner detection sensor 43 Developing part toner detection sensor 44 Developing part toner detection sensor 47 Light emitting element 48 Light receiving element 70 Toner density Sensor 100 Image forming apparatus 101 First detection unit 102 Determination unit 103 First control unit 104 Second control unit 105 Toner replenishment unit 106 Second detection unit 107 Third control unit 108 Fourth control unit 109 Fifth control unit 200 Image formation Apparatus 300 image forming apparatus

JP 2006-65079 A JP 2007-025563 A

Claims (8)

A developing unit for developing the electrostatic latent image formed on the image carrier with toner;
A first detection unit for detecting a toner amount in the developing unit;
Based on a value indicating variation in the toner amount detected by the first detection unit at each of a plurality of sampling timings within a predetermined period, whether or not an abnormality has occurred in the first detection unit, or the development A determination unit that determines whether the toner is full in the unit;
Image forming apparatus. The determination unit indicates a variation in the toner amount detected by the first detection unit at each sampling timing, and the toner amount detected by the first detection unit at each sampling timing exceeds the first threshold value. When the value is equal to or less than the second threshold, it is determined that an abnormality has occurred in the first detection unit.
The image forming apparatus according to claim 1. The determination unit indicates a variation in the toner amount detected by the first detection unit at each sampling timing, and the toner amount detected by the first detection unit at each sampling timing exceeds the first threshold value. When the value exceeds the second threshold, it is determined that the toner is full in the developing unit.
The image forming apparatus according to claim 1. A first control unit that performs control to stop the image forming operation when the determination unit determines that an abnormality has occurred in the first detection unit;
The image forming apparatus according to claim 1. A stirring unit for stirring the toner in the developing unit;
A second control unit that performs control to increase the stirring speed by the stirring unit when the determination unit determines that an abnormality has occurred in the first detection unit;
The image forming apparatus according to claim 1. A second detector for detecting a density of a toner image indicating the electrostatic latent image developed with toner;
When the determination unit determines that an abnormality has occurred in the first detection unit and the density of the toner image detected by the second detection unit is normal, the image forming operation is continued. A third control unit that performs control,
The image forming apparatus according to claim 1. A fourth control unit that performs control to forcibly discharge the toner in the developing unit when the determination unit determines that the toner in the developing unit is full;
The image forming apparatus according to claim 1. A second detector for detecting a density of a toner image indicating the electrostatic latent image developed with toner;
When the determination unit determines that the toner in the developing unit is full, control is performed to perform toner density adjustment based on the density of the toner image detected by the second detection unit. A control unit;
The image forming apparatus according to claim 1.

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