JP2012083645A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that keeps the proper amount of toner in a developing unit to prevent toner to be oversupplied in supplying toner by toner remaining amount detection.SOLUTION: An image forming apparatus comprises a detection times counter that counts the number of times that a toner remaining amount detection sensor 18d detects that toner accommodated in a developing unit 18 is not less than the predetermined amount for every predetermined period. When the count value of the detection times counter is not more than the predetermined value, the image forming apparatus supplies toner from a sub-hopper 17 to the developing unit 18; and when the count value of the detection times counter begins to increase, stops supplying toner from the sub-hopper 17 to the developing unit 18.

Description

  The present invention relates to an image forming apparatus that forms an image by supplying toner from a toner storage container to a developing unit via a toner storage chamber.

  The electrophotographic image forming apparatus forms an electrostatic latent image on the surface of a photosensitive drum as an image carrier, develops the latent image with toner to form a visible image, and transfers the image to a recording medium to form an image. To do. In such an image forming apparatus, there is an image forming apparatus in which toner that is a consumable can be replenished by replacing a toner container that contains toner with respect to the apparatus main body.

  In the configuration in which the toner is supplied from the toner storage container, the toner is not supplied directly from the toner storage container to the developing unit, but a sub hopper serving as an intermediate toner storing means is interposed between the toner storage container and the developing unit. It is common. That is, the toner is supplied from the toner container to the sub hopper, and when the toner in the developing unit runs out, the toner supplying means of the sub hopper operates to supply the toner to the developing unit.

  Specifically, a toner agitating unit that agitates the toner and has a toner supply or toner conveyance function and a toner remaining amount detection sensor are provided in each of the sub hopper and the developing device. If the toner in the developing unit is determined to be “no toner” from the result of detecting the remaining amount of toner in the developing unit, the sub-hopper upstream is requested to supply the toner and the toner is supplied. Is.

  In the case of the above-described toner supply type developing device, it is necessary to accurately detect the remaining amount of toner in the developing device in order to keep the toner amount in the developing device appropriately. However, due to the arrangement of the sub hopper and the toner remaining amount detection sensor, in actuality, even if the toner is supplied from the sub hopper, the physical distance is delayed until the supplied toner is detected in the developing device. Occurs. That is, the developing device has a developing roller having a length substantially the same as the width of the recording medium, and it is necessary to supply toner to the peripheral surface of the developing roller. Therefore, the toner supplied from the sub hopper is supplied to the developing roller. The developer is stirred and conveyed from one end side to the other end side in the longitudinal direction of the developing device. For this reason, in the developing device, the toner receiving portion (toner dropping point) from the sub hopper is arranged on one end side in the longitudinal direction, and the toner remaining amount detection sensor is arranged on the other end side in the longitudinal direction. Thus, even when toner is supplied from the sub hopper to the developing device, a time lag occurs until the toner is agitated and conveyed in the longitudinal direction of the developing device and reaches the toner remaining amount detection sensor position.

  Even if sufficient toner is supplied from the sub hopper to the developing device due to the time lag, if the developing device determines that there is no toner before the toner is detected by the toner remaining amount detection sensor, the toner is supplied to the sub hopper. Requests can happen. In such a case, the toner is actually supplied excessively into the developing device, and toner leakage may occur from the developing device.

  As a proposal for solving this, as shown in Patent Document 1, “toner present” / “no toner” detected by the toner remaining amount detecting means in a state where toner is supplied from the sub hopper to the developing device. Some devices stop the supply of toner from the sub hopper based on the detection state and the transition of the detection value of the toner remaining amount detecting means that falls by its own weight. In other words, the toner remaining amount is detected while the toner is being supplied, and the toner supply is stopped by judging the toner remaining amount while observing the transition of the detection value for detecting the “toner present”.

JP 2006-72145 A

  However, if the toner supply is stopped while watching the transition of the detected value of the change in the remaining amount of toner as in the configuration of Patent Document 1, it is difficult to eliminate the excessive supply state that needs to be stopped immediately.

  The present invention has been made in view of the above points, and an object of the present invention is to appropriately maintain the remaining amount of toner in the developing unit when toner is supplied by detecting the remaining amount of toner and to prevent excessive supply. The present invention provides an image forming apparatus capable of achieving the above.

  In order to achieve the above object, a typical configuration according to the present invention includes a toner storage container storing toner, a toner storage means for receiving toner from the toner storage container, and supplying toner from the toner storage means. A developing unit that develops the electrostatic latent image formed on the image bearing member with toner, and a toner supply unit that supplies toner in the toner storage unit to the developing unit; and the toner A toner conveying means for conveying the toner supplied from the accommodating means from one end side to the other end side in the longitudinal direction in the developing unit; and whether there is a predetermined amount or more of toner in the developing unit within a predetermined period A toner remaining amount detecting means for repeatedly detecting whether the toner remaining amount detecting means has a predetermined amount or more of toner in the developing unit every predetermined period. A detection counter that counts the number of times of detection, and when the count value of the detection counter is equal to or less than a predetermined value, the toner is supplied from the toner storage unit to the developing unit, and the toner from the toner storage unit After the supply, when the count value of the detection number counter for each predetermined period starts to increase, the toner supply from the toner storage unit to the developing unit is stopped.

  In the present invention, the toner supply from the toner containing means to the developing unit is stopped when the number of times that “toner is present” is detected within a predetermined period by the toner remaining amount detecting means, so that It is possible to reliably prevent oversupply.

1 is an explanatory diagram of an overall configuration of an image forming apparatus. FIG. 2 is a cross-sectional view of a developing device. FIG. 3 is a configuration explanatory diagram of a developing device. It is explanatory drawing of a sub hopper. It is explanatory drawing of a developing unit. 6 is a timing chart showing toner supply timing with respect to a toner remaining amount detection result of a development unit at the start of development. 6 is a timing chart showing toner remaining amount detection start timing of a developing unit and toner supply start timing by a sub hopper. FIG. 4 is a block diagram illustrating a control configuration that performs toner supply control. 6 is a flowchart for explaining a toner supply request and a toner supply operation. 6 is a timing chart illustrating a toner supply end sequence.

  Next, an image forming apparatus according to an embodiment for carrying out the present invention will be described with reference to the drawings.

[First Embodiment]
<Overall configuration of image forming apparatus>
First, the overall configuration of the image forming apparatus according to the first embodiment will be described together with the image forming operation with reference to FIG. FIG. 1 is a schematic cross-sectional explanatory diagram of an electrophotographic copying machine which is an image forming apparatus according to the first embodiment.

  The image forming apparatus according to the present exemplary embodiment includes an image forming unit that forms an image inside the apparatus main body 1. In this image forming section, a photosensitive drum 2 as an image carrier is rotatably provided. Around the photosensitive drum 2, a charging roller 3, a laser exposure unit 4, a developing device 5, A transfer roller 6 and a cleaning member 7 are disposed.

  In addition, a universal cassette (not shown) in which a recording medium P such as a sheet is accommodated can be inserted and removed freely at the lower part of the apparatus main body 1, and the recording medium in the cassette is arranged between the photosensitive drum 2 and the transfer roller 6. Conveying means 9 having a conveying belt 8 and the like for conveying to a transfer portion which is a nip portion is provided.

  When forming an image, the laser exposure unit 4 irradiates the photosensitive drum 2 with laser light corresponding to the image signal. The photosensitive drum 2 is uniformly charged by applying a bias by the charging roller 3, and an electrostatic latent image is formed by the laser light irradiation. The electrostatic latent image is developed with toner by the developing device 5 to form a visible image.

  In synchronism with the image formation, the recording medium is conveyed from the universal cassette to the nip portion between the photosensitive drum 2 and the transfer roller 6 so as to synchronize with the image forming operation described above. The toner image on the photosensitive drum 2 is transferred to the recording medium by applying a bias.

  The recording medium onto which the toner image has been transferred is conveyed to a fixing means (not shown), where the toner image is fixed by heating and pressing, and then discharged to a discharge portion. Further, the toner remaining on the photosensitive drum 2 after the toner image is transferred to the recording medium P is removed by the cleaning member 7.

<Developing device>
Next, a developing device for developing the electrostatic latent image formed on the photosensitive drum 2 with toner will be described.

  As shown in the cross section of FIG. 2 and the perspective view of FIG. 3, the developing device 5 of the present embodiment includes a toner bottle 16 containing toner, a sub hopper 17 that receives supply of toner from the toner bottle 16, and a toner from the sub hopper 17. And a developing unit 18 that develops the electrostatic latent image formed on the photosensitive drum 2 with toner.

  The toner bottle 16 is a cylindrical toner storage container that is detachably attached to the apparatus main body, and the toner bottle storing the toner is rotatably mounted on the apparatus main body. As the toner bottle 16 rotates, the toner in the bottle is supplied to the sub hopper 17 which is a toner containing means. The sub hopper 17 temporarily stores toner supplied from the toner bottle 16 to the developing unit 18 and supplies a certain amount of toner to the developing unit 18 in response to a toner request signal from the developing unit 18.

  In the developing unit 18, a developing roller 19 is disposed in the vicinity of the photosensitive drum 2, and toner is formed in a spike shape on the peripheral surface of the rotating developing roller 19 by the developing roller 19 and a magnet roller (not shown) therein. To be attached. Then, the toner is attached to the developing roller 19 so that development is performed by attaching the toner in accordance with the electrostatic latent image formed on the photosensitive drum 2 by applying a developing bias.

  The developing roller 19 rotates only during the developing period by transmitting and interrupting the driving force of the main motor that drives the main members of the apparatus main body by the roller clutch.

  In the developing device 5 of the present embodiment, as shown in FIG. 8, a control unit 20 having a CPU, a ROM, and a RAM controls driving of the main motor M0 and the developing roller clutch CL during image formation. Further, as will be described later, the control unit 20 controls the driving of the bottle motor M1 in response to a request from the sub hopper 17, and controls the driving of the hopper motor M2 in response to a request from the developing unit 18 to supply toner to the developing unit 18. I do.

  3 is an explanatory view of the arrangement of the toner bottle 16, the sub hopper 17, and the developing unit 18. FIG. 4 is an internal explanatory view of the sub hopper 17. FIG. 5 is an internal explanatory view of the developing unit 18.

  A cap (not shown) is provided at the tip of the cylindrical toner bottle 16, and when the cap engages with a coupling 17a (see FIG. 4) provided on the sub hopper 17, the cap is opened. Thus, the toner can be discharged into the toner containing means which is a sub hopper. Further, the toner bottle 16 is formed with spiral irregularities 16a (see FIG. 3) on the outer periphery, and the toner bottle 16 is rotated by driving the bottle motor M1 to move the toner in the bottle to the arrow in FIG. The toner can be supplied to the sub hopper 17 by being conveyed in the a direction.

  As shown in FIG. 4, the sub hopper 17 is provided with a coupling 17 a that engages with a cap of the toner bottle 16 so as to be rotatable by a bottle motor M <b> 1, and a supply port 17 b for supplying toner to the developing unit 18 at the lower part. Is formed. Further, the sub hopper 17 is provided with a stirring screw 17c as a toner supplying means for rotating the toner in the sub hopper 17 and supplying the toner to the developing unit 18 from the supply port 17b. Thus, when the stirring screw 17c rotates by a predetermined amount by the hopper motor M2, a predetermined amount of toner is dropped and supplied from the supply port 17b into the developing unit.

  Further, the sub hopper 17 is provided with a hopper remaining detection sensor 17d as a first toner remaining amount detecting means for detecting the remaining amount of toner inside. When the remaining amount of toner in the hopper decreases below a predetermined amount according to the detection result by the hopper residual detection sensor 17d, the toner bottle 16 is rotated to replenish the sub hopper 17 with toner.

  As shown in FIG. 5, the developing unit 18 has a developing roller 19 accommodated in a long developing frame. A toner stirring chamber 18a for supplying the stirred toner to the developing roller 19 is formed. In the toner stirring chamber 18a, a stirring screw 18b is rotatably provided as a toner transporting means for transporting the toner while stirring the toner from one end side to the other end side in the longitudinal direction.

  In addition, a toner receiving portion 18c that receives toner supplied from the sub hopper 17 is disposed on one end side in the longitudinal direction of the toner stirring chamber 18a. The toner dropped from the sub hopper 17 to the toner receiving portion 18c is conveyed while being stirred from one end in the longitudinal direction of the toner stirring chamber 18a to the other end in the longitudinal direction by the rotation of the stirring screw 18b. A development residual detection sensor 18d as a second toner remaining amount detecting means for detecting the remaining amount of toner in the toner stirring chamber 18a is provided on the other end side in the longitudinal direction. That is, the toner remaining amount detection position in the developing unit 18 is arranged on the other end side in the longitudinal direction of the developing unit.

  When the remaining amount of toner in the toner stirring chamber decreases below a predetermined amount according to the result of detection of the remaining amount of toner by the development residual detection sensor 18d, the sub hopper 17 is requested to supply toner, and the stirring screw 17c is driven to drive the toner. Get replenished.

  The actuators such as the bottle motor M1, the hopper motor M2, and the roller clutch CL can be operated only while the main motor M0 is operating.

<Toner supply to development unit>
Next, a toner supply configuration to the developing unit 18 will be described.

  In the developing device of this embodiment, toner is supplied from the toner bottle 16 to the sub hopper 17. The toner is supplied from the toner bottle 16 to the sub hopper 17 because the hopper residual detection sensor 17d detects that the amount of toner in the sub hopper 17 is equal to or less than a predetermined amount. Is determined. In the present embodiment, the remaining amount of toner is detected by the hopper remaining detection sensor 17d during the period in which the toner is supplied from the sub hopper 17 to the developing unit 18. That is, the toner remaining amount detection period by the hopper remaining detection sensor 17d and the toner supply period to the developing unit 18 by the sub hopper 17 are the same.

  The toner supply from the sub hopper 17 to the developing unit 18 is performed when it is detected that the toner in the developing unit 18 has become a predetermined amount or less by the development residual detection sensor 18d, and “no toner” is determined. At this time, by detecting “no toner” by the development residual detection sensor 18d, the sub hopper 17 is requested to supply toner, and the toner supplied from the sub hopper 17 is actually detected by the development residual detection sensor 18d. As described above, there is a time lag. That is, the toner dropped from the sub hopper 17 to the one end side in the longitudinal direction of the developing unit 18 is conveyed to the other end side in the longitudinal direction of the developing unit 18 by the stirring screw 18b and is not supplied with toner until reaching the development residual detection sensor 18d. It is a mechanism that can be detected.

  A problem arises when the sub hopper 17 supplies more toner than the developing unit 18 needs due to the time lag. Next, a situation where extra toner is supplied from the sub hopper 17 to the developing unit 18 will be described.

(Toner remaining amount detection and toner supply at the start of image formation)
FIG. 6A is a timing chart in the case where an extra toner supply is performed in the toner supply operation during image formation.

  The development residual detection sensor 18d can detect the remaining amount of toner only while the main motor M0 and the development roller clutch CL are operating, that is, only during the developing period. Similarly, the hopper residual detection sensor 17d has a condition that the remaining amount of toner can be detected only while the main motor M0 and the hopper motor M2 are operating. When these conditions are satisfied, the toner remaining amount is detected by the toner remaining detection sensor.

  The development residual detection sensor 18d repeatedly detects whether or not there is a predetermined amount or more of toner in the development unit within a predetermined period. In the development residual detection sensor 18d of the present embodiment, the remaining amount of toner in the development unit 18 is detected during the development period of 1500 (ms). Then, during the toner remaining amount detection period of 1500 (ms), it is detected 15 times in units of 100 (ms) whether or not there is a predetermined amount or more of toner in the toner stirring chamber 18a. The development remaining detection sensor 18d is turned on when detecting that the toner is more than a predetermined amount upon detection, and is turned off when not detected.

  Further, in the present embodiment, as shown in FIG. 8, a detection number counter 23 is provided for counting the number of times (the number of times the toner has been turned on) that the development residual detection sensor 18d has detected that the toner is a predetermined amount or more. Yes. When the count value of the detection number counter 23 is equal to or smaller than a predetermined value, toner is supplied from the sub hopper 17 to the developing unit 18. In this embodiment, based on the count value of the detection number counter 23, when it is detected that there is a predetermined amount or more of toner three times or more during the toner remaining amount detection period, it is determined that “there is toner” in the developing unit 18. If it is less than 2 times, “no toner” is determined.

  If it is determined that there is no toner as a result of the detection, a request for toner supply to the sub hopper 17 is made, and the hopper motor M2 rotates to supply a constant amount of toner to the developing unit 18. While the hopper motor M2 is rotating, the remaining amount of toner in the sub hopper 17 is also detected by the hopper residual detection sensor 17d.

  Here, when the toner supply detection timing coincides with the toner supply start timing and the toner supply is performed, the toner remaining detection result for determining whether or not to supply the toner is actually the detection performed once before. It will be determined by the result. Therefore, assuming that the previous detection result by the development residual detection sensor is “no toner” at the start of image formation, as shown in FIG. 6A, in the first development period when image formation is started, the memory The hopper motor M2 is driven in accordance with the previous detection result stored in the toner to supply toner (z). When the toner remaining amount detection result in the detection period (A) corresponding to the first development period after the start of image formation detects “no toner”, the hopper motor M2 is driven in response to this and the toner supply (a) To do. Similarly, toner is supplied (b) when “no toner” is detected in the detection period (B). When the detection result of the detection period (C) detects “with toner”, the driving of the hopper motor M2 is stopped in accordance with this, and the toner supply is stopped. In this embodiment, as will be described later, the toner supply from the sub hopper 17 to the developing unit 18 is stopped when the number of times the development remaining detection sensor 18d is turned on (the count value of the detection number counter 23) is the remaining development amount in the previous detection period. When the number of times the detection sensor 18d is turned on increases, the toner supply is stopped.

  Therefore, the toner supply from the sub hopper 17 is (z) (a) (b) even though the “toner-free” detection by the development residual detection sensor 18d from the start of image formation is performed twice (A) and (B). ) Three times, resulting in a situation where toner is excessively supplied.

  Therefore, in the present embodiment, as shown in FIG. 6B, at the start of image formation, even if the previous toner remaining amount detection result is “no toner”, the toner is supplied from the sub hopper 17. Absent.

  The toner supply is performed based on the result of detecting the remaining amount of toner after the start of image formation. That is, as shown in FIG. 6B, when the toner remaining amount detection result in the first detection period (A) after the start of image formation detects “no toner”, the hopper motor M2 is driven accordingly. Supply toner (a). Further, toner is supplied (b) when “no toner” is detected in the detection period (B). Then, when the detection result in the next detection period (C) indicates that the count value of the detection number counter 23 increases and “toner is present” is detected, the driving of the hopper motor M2 is stopped and the toner supply is stopped accordingly. To do. As a result, the toner supply from the sub hopper 17 is two times (a) and (b) corresponding to the “no toner” detection (A) and (B) twice by the development residual detection sensor 18d. Compared to the case of FIG. 6A, the number of times the toner is supplied from the sub hopper 17 is reduced by one.

  As described above, in the present embodiment, the sub hopper 17 supplies toner in response to the “no toner” detection by the development residual detection sensor 18d after the start of image formation, thereby preventing excessive supply of toner.

(Toner remaining amount detection period and toner supply period)
Next, the toner remaining amount detection start and toner supply start timing will be described. When the start timing of the remaining toner detection of the development residual detection sensor 18d and the toner supply start timing by the sub hopper 17 are not synchronized and operated independently, the timing at which the remaining toner detection period ends, that is, the toner supply required The determination timing of “no” may deviate from the timing of completion of toner supply per time by the sub hopper 17. Then, immediately before the remaining toner detection result by the development residual detection sensor 18d changes from “no toner” to “toner present”, the sub hopper 17 starts to supply toner in response to the previous “no toner” detection result. Will occur. This is because, due to the time lag described above, although the developing unit 18 has been supplied with toner to a state where there is toner, the detection was delayed, so the sub-hopper 17 has exceeded one time by the previous “no toner” detection result. A large amount of toner will be supplied.

  Therefore, in this embodiment, the start timing of the remaining toner detection of the development residual detection sensor 18d and the start timing of toner supply by the sub hopper 17 coincide with each other so that the above-described deviation does not occur. In this embodiment, the toner supply period by the sub hopper 17 is shorter than the toner remaining amount detection period of the developing unit 18 by the development residual detection sensor 18d.

  That is, as shown in the timing chart of FIG. 7, when the remaining toner amount detection period by the development residual detection sensor 18d is X (ms), the toner supply period by the sub hopper 17 is set to the remaining toner amount detection period X (ms). Shorter period Y (ms).

  The period of XY ≧ Z is a period in which the development residual detection sensor 18d detects the result of the sub hopper 17 supplying the toner in response to the toner supply request from the developing unit 18. Whether the toner supply is requested again can be reflected based on the detection result in the period Z.

  Therefore, the toner remaining amount detection period of the developing unit 18 is X (ms), the toner supply period Y (ms) that also serves as a stirring operation for performing the toner supply process from the sub hopper 17, and the development residual detection sensor 18d. The relationship with the period Z (ms) in which whether or not the toner remaining amount is detected and whether or not the toner supply request is requested again is set as follows.

X (ms) ≧ Y (ms) + Z (ms)
As described above, by setting the relationship between the toner detection time of the developing unit 18 and the sub hopper 17 and the reflection time of the toner supply result, the toner supply for the toner supply request can be accurately performed. Further, the relationship between the number of toner requests from the developing unit 18 and the number of toner supply from the sub hopper 17 can always be a one-to-one relationship, and one replenishment is always executed for one request. Thus, excessive toner supply from the sub hopper 17 to the developing unit 18 can be prevented.

<Toner supply control to development unit>
Next, a control configuration of toner supply by the sub hopper 17 in response to a toner supply request based on a detection result by the development residual detection sensor 18d will be described based on a control block diagram of FIG. 8 and an operation flowchart of FIG.

  In the toner supply control configuration of this embodiment, as shown in FIG. 8, a control unit 20 having a CPU, a ROM, and a RAM inputs detection signals from a hopper residual detection sensor 17d, a development residual detection sensor 18d, and the like. Based on the signals, the bottle motor M1 and the hopper motor M2 are driven and controlled. In FIG. 8, the request counter unit 21 is a counter for counting the number of times the sub hopper 17 has requested supply of toner to the development unit 18 based on the detection result of the development residual detection sensor 18 d. The supply counter unit 22 is a counter that counts the number of times the sub hopper 17 supplies toner to the developing unit 18. Further, the detection number counter 23 is a counter that counts the number of times the development residual detection sensor 18d detects that the toner is more than a predetermined amount.

  In the above configuration, first, it is determined whether or not a condition for starting the operation of the developing unit 18 is satisfied (S1). That is, since the operation cannot be started unless the main motor M0 and the developing roller clutch CL are ON, the processing ends.

(Toner supply started)
In step S1, if the start condition is satisfied, the developing unit 18 starts to operate. At the same time, the toner agitating operation in the developing unit 18 is performed, and accordingly, the development by the development residual sensor 18d is performed. The toner remaining amount in the unit 18 is detected (S2). In the toner remaining amount detection, as described above, the toner stirring chamber 18a is detected 15 times in units of 100 (ms) during the toner remaining amount detection period of 1500 (ms). At this time, the value of the number of times that the toner is detected to be a predetermined amount or more (the count value of the detection number counter 23) is stored in the memory.

  When the count value of the number of times that the toner is detected to be greater than or equal to the predetermined amount is 2 times or less, it is determined that there is no toner, and when it is 3 times or more, it is determined that there is toner. If it is determined that there is “toner” based on the detection result, there is no need for toner replenishment, so the process proceeds to step S10, where the number of toner requests and the number of toner supply are cleared, and the process ends.

  However, if it is determined in step 2 that there is no toner, a toner request is made to the developing unit 18 to the sub hopper 17 and the count number of the toner request counter is incremented by one (S3).

  Next, it is determined whether or not the count value of the detection number counter 23 is larger than the count value when detected in the previous detection period (S4). When the count value has not increased, it is necessary to supply toner to the developing unit 18. At this time, in this embodiment, the toner is not supplied from the sub hopper 17 more times than the number of times the toner is requested from the developing unit 18. Therefore, the process proceeds to step 6, where the control unit supplies the toner counter counter 21, which is the number of times toner is requested from the developing unit 18 to the sub hopper 17, and the supply counter unit, which is the number of times toner is supplied from the sub hopper 17 to the developing unit 18. It is determined whether the count value is 22 or less.

  If the toner has not been supplied for the required number of times, it is determined whether or not the sub hopper motor M2 is rotating (S7). If the hopper motor M2 is already ON at this time, the toner supply operation is executed. Judge that it is inside. On the other hand, if the hopper motor M2 is stopped, the sub hopper motor is turned on (S8), the toner supply is started, and at the same time, the count number of the execution counter is incremented by 1 (S9), and the process returns to step 1.

  By controlling the toner supply as described above, even if a deviation occurs in the toner supply operation timing due to whether or not the operation condition is satisfied, the number of toner supply from the sub hopper 17 to the developing unit 18 is less than the number of times the toner supply is requested. Therefore, the number of toner supply is limited. In this way, toner supply exceeding the required number of toners is prevented, and excessive supply of toner to the developing unit 18 is prevented.

(Toner supply stop)
As described above, the toner is supplied from the sub hopper 17 to the developing unit 18, and the supply of the toner is stopped when it is detected by the development residual detection sensor 18d that the toner amount is a predetermined amount or more. Next, the toner supply stop control will be specifically described.

  In the present embodiment, as described above, whether or not there is a predetermined amount or more of toner in the toner agitating chamber 18a in units of 100 (ms) during the toner remaining amount detection period of 1500 (ms). Detect by 18d. Therefore, in this embodiment, the presence / absence of toner is detected 15 times within the toner remaining amount detection period, and when it is detected that there is a predetermined amount or more of toner three times or more, it is determined that “toner is present”.

  At this time, after the toner is supplied from the sub hopper 17, the number of times the development residual detection sensor 18d is turned ON within the toner remaining amount detection period, that is, the count value of the detection number counter 23 is the detection number counter within the previous toner remaining amount detection period. When the count value of 23 starts to increase, the toner supply from the sub hopper 17 is stopped for the time being. For example, as shown in FIG. 10, if the count value of the detection number counter 23 is “0” during the detection period (A), the toner is supplied (a) from the sub hopper 17 to the developing unit 18. Then, if the count value of the detection number counter 23 is “2” in the next detection period (B), when the count value starts to increase from the previous count value “0” (the count value is “1”). The toner supply (a) from the sub hopper 17 to the developing unit 18 is stopped. Then, the process proceeds to step S10 in the flowchart of FIG. 9 to clear the toner request count and the toner supply count.

  However, since the count value of the detection number counter 23 in this detection period (B) is “2” (predetermined number of times), it is determined that there is no toner, and in response to this, the toner supply (b ) Is made.

  In this embodiment, as a pattern in which the count value of the detection number counter 23 starts to increase, the count value starts to increase when it changes from “0” to “1” or from “1” to “2”. At that time, the toner supply from the sub hopper 17 is stopped. However, the toner is again supplied from the sub hopper 17 in order to determine that “no toner” thereafter. On the other hand, when the count value that has started to increase is equal to or greater than “3”, the toner supply from the sub hopper 17 is stopped when the count value starts to increase, and at this time, it is determined that “toner is present”. Therefore, the toner supply is stopped as it is.

  In this way, when the number of toner detections by the development residual detection sensor 18d increases from the previous time, the toner supply from the sub hopper 17 is stopped, so that excessive toner supply can be reliably prevented.

CL: roller clutch M0 ... main motor M1 ... bottle motor M2 ... hopper motor P ... recording medium 1 ... device body 2 ... photoconductor drum 3 ... charging roller 4 ... laser exposure means 5 ... developing device 6 ... transfer roller 7 ... cleaning member 8 ... Conveying belt 9 ... Conveying means 16 ... Toner bottle 16a ... Concavity and convexity 17 ... Sub hopper 17a ... Coupling 17b ... Supply port 17c ... Stirring screw 17d ... Hopper residual detection sensor 18 ... Developing unit 18a ... Toner stirring chamber 18b ... Stirring screw 18c ... Toner receiving portion 18d ... development residual detection sensor 19 ... developing roller 20 ... control portion 21 ... request counter portion 22 ... supply counter portion 23 ... detection frequency counter

Claims (4)

A toner container that contains toner, a toner container that receives toner from the toner container, a toner container that receives toner from the toner container, and develops an electrostatic latent image formed on the image carrier. In an image forming apparatus having a developing unit,
Toner supply means for supplying toner in the toner storage means to the development unit;
A toner conveying means for conveying the toner supplied from the toner accommodating means from one end side in the longitudinal direction in the developing unit to the other end side;
Toner remaining amount detecting means for repeatedly detecting whether or not a predetermined amount of toner is present in the developing unit within a predetermined period;
A detection number counter that counts the number of times that the toner remaining amount detecting means detects that there is a predetermined amount or more of toner in the developing unit for each predetermined period;
Have
When the count value of the detection number counter is less than or equal to a predetermined value, toner is supplied from the toner containing means to the developing unit,
After the toner supply from the toner storage unit, the toner supply from the toner storage unit to the developing unit is stopped when the count value of the detection number counter for each predetermined period starts to increase. Forming equipment. A toner receiving portion where the developing unit receives toner supply from the toner supplying means is on one end side in the longitudinal direction of the developing unit;
2. The image forming apparatus according to claim 1, wherein the toner remaining amount detecting position by the toner remaining amount detecting means is on the other end side in the longitudinal direction of the developing unit.   The detection by the toner remaining amount detection means is performed during a period in which the developing unit is driven and developing, and toner is supplied according to a detection result after the start of image formation. Item 3. The image forming apparatus according to Item 2. A supply counter for counting the number of times toner is supplied from the toner storage means to the developing unit;
A request counter unit that counts the number of times toner supply is requested to the toner storage unit according to a detection result of the toner remaining amount detection unit;
Have
Limiting the number of toner supply times from the count values of the supply counter unit and the request counter unit so that the toner supply frequency from the toner storage unit to the developing unit is equal to or less than the number of times the toner supply is requested. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.

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