JP5510363B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus configured to optically detect the amount of developer in a replaceable cartridge.

  Conventionally, an image forming apparatus configured to optically detect the amount of developer in a replaceable cartridge is known. For example, Patent Document 1 includes a pair of light transmission windows opposed to the side walls of the cartridge, and a cartridge based on a light reception signal obtained by detecting light incident from one light transmission window from the other light transmission window. A configuration for detecting the remaining amount of the developer is disclosed. In the image forming apparatus, for example, the cartridge replacement time is determined based on the detected amount of developer in the cartridge.

Japanese Patent Laid-Open No. 2001-5276

  By the way, it is known that the developer in the cartridge gradually deteriorates in charging performance due to repeated friction between the developing roller and the layer thickness regulating blade or repeated stirring by the stirring member. Yes. Therefore, in an image forming apparatus, it has been studied to reduce the number of rotations of the developing roller and the stirring member during operation. In this case, particularly in a situation where the number of printed sheets is small in one image forming operation, It has been found that the replacement time may not be determined accurately.

  That is, the developer in the cartridge is scattered in the cartridge by the rotation of the stirring member. However, when the amount of the developer is reduced, the developer accumulated at the bottom is sufficiently scattered in the initial rotation of the stirring member. Therefore, the incident light easily passes through the cartridge, and the amount of light received by the light receiving element (the intensity of the received light) increases. Therefore, when the cartridge replacement timing is determined at the initial stage of rotation of the stirring member (when the number of printed sheets in one image forming operation is small), the cartridge should be replaced even though sufficient developer remains. It may be determined that it is time.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that can accurately determine the replacement timing of a cartridge while suppressing a decrease in developer charging performance. Objective.

In order to achieve the above-described object, the image forming apparatus of the present invention includes a stirring member that stirs the developer by rotating and a developing roller that carries the developer, and the driving force is input to the image forming apparatus. An image forming apparatus configured to optically detect an amount of developer in a replaceable cartridge configured such that a stirring member and the developing roller rotate together, and emits light into the cartridge A light receiving element that receives light emitted from the light emitting element and passed through the cartridge, and an amount of light received by the light receiving element when the stirring member continuously rotates more than a predetermined number of times A determination unit that determines whether or not the determination target value exceeds a determination threshold value, and determines that the cartridge is at a replacement time when the determination target value exceeds the determination threshold value. image While a print job that is sufficient to rotate the stirring member below the predetermined number of times to complete the composition operation is continuously input, an index value serving as an index of the amount of developer used is counted, If the count value exceeds a predetermined value, the agitation member is continuously rotated more than the predetermined number of times when an image forming operation based on a print job input next time is performed, and the determination target value is It is characterized by determining whether it exceeded the determination threshold value.

  Here, in the present invention, a print job in which it is sufficient to rotate the stirring member a predetermined number of times or less to complete the image forming operation means that the number of printed sheets in one image forming operation is small, and therefore the stirring member is rotated. It means a print job whose number of times is equal to or less than a predetermined number. The predetermined number of times, in each case of the number of rotations of the stirring member exceeding the number of times and the number of rotations of the stirring member less than the number of times, the determination target value based on the amount of light received by the light receiving element exceeds the determination threshold value. This means the number of rotations of the agitating member that becomes the boundary such that the determination result differs.

  According to the image forming apparatus configured as described above, the determination unit counts an index value serving as an index of the amount of developer used while a print job with a small number of printed sheets is continuously input. Since the cartridge replacement time is determined when the value exceeds a predetermined value, for example, after completion of the image forming operation based on a print job with a small number of printed sheets, the replacement time is determined by rotating the stirring member extra each time. Compared to the case, the total number of rotations of the stirring member can be reduced. In addition, this makes it possible to reduce the total number of rotations of the developing roller configured to rotate with the agitating member, thereby suppressing a decrease in developer charging performance.

  The cartridge replacement timing is determined after the stirring member is continuously rotated more than a predetermined number of times and the developer in the cartridge is sufficiently scattered, so that the cartridge replacement timing can be accurately determined. it can.

An image forming apparatus according to another aspect includes a stirring member that stirs the developer by rotating and a developing roller that carries the developer, and the stirring member and the An image forming apparatus configured to optically detect an amount of developer in a replaceable cartridge configured to rotate together with a developing roller, the light emitting element configured to emit light into the cartridge A light-receiving element that receives light emitted from the light-emitting element and passed through the cartridge, and a determination target based on the amount of light received by the light-receiving element when the stirring member continuously rotates more than a predetermined number of times Determining means for determining whether or not the value exceeds a determination threshold value, and determining that the cartridge is at a replacement time when the determination target value exceeds the determination threshold value, wherein the determination means includes the stirring member Said place For each longer predetermined interval than the time to count the rotation, the decision target value by rotating beyond the predetermined number of consecutive said agitation member and judging whether exceeds the determination threshold.

  According to the image forming apparatus configured as described above, the determination unit determines the replacement time of the cartridge at predetermined intervals longer than the time required for the stirring member to rotate a predetermined number of times. After the completion of the image forming operation based on the print job, the total number of rotations of the agitating member and the developing roller can be reduced as compared with the case of determining the cartridge replacement time every time. Thereby, the fall of the charging performance of a developer can be suppressed. In addition, since the cartridge replacement time is determined after the stirring member is continuously rotated more than a predetermined number of times, the cartridge replacement time can be accurately determined.

  According to the present invention, it is possible to accurately determine the replacement time of the cartridge while suppressing a decrease in the charging performance of the developer.

1 is a diagram illustrating a schematic configuration of a laser printer as an example of an image forming apparatus according to an embodiment of the present invention. FIG. 4 is a cross-sectional view (a) and a side view (b) of the developing cartridge. FIG. 3 is a cross-sectional view taken along the line XX of FIG. It is a time chart which shows the output voltage value of a light receiving element, and is a figure (a) showing a case where a count value exceeds a predetermined value, and a figure (b) showing a case where a count value does not exceed a predetermined value. It is a flowchart which shows the control in a laser printer. It is explanatory drawing of the control after the count value concerning 2nd Embodiment exceeds predetermined value, the figure (a) which shows the time when the continuous print job is input next time, and the one sheet print job is input next time FIG. It is explanatory drawing of control after the count value which concerns on 3rd Embodiment exceeds predetermined value. It is a flowchart which shows control of the laser printer which concerns on 4th Embodiment.

[First Embodiment]
Next, a first embodiment showing a basic configuration will be described in detail with reference to the drawings as appropriate. In the following description, first, a brief description of the general configuration of a laser printer 1 as an example of an image forming apparatus, the detailed configuration and operation of Le Zapurinta 1 will be described.

  Here, in the following description, the direction will be described with reference to the user who uses the laser printer 1. That is, the right side in FIG. 1 is “front”, the left side is “rear”, the front side is “left”, and the back side is “right”. Also, the vertical direction in FIG.

<Schematic configuration of laser printer>
As shown in FIG. 1, the laser printer 1 is a process of transferring a toner image (developer image) onto a paper feed unit 3 that supplies a paper S, an exposure device 4, and the paper S in a main body housing 2. It mainly includes a cartridge 5 and a fixing device 8 that thermally fixes the toner image on the paper S.

  The paper feed unit 3 is provided at a lower portion in the main body housing 2, and mainly includes a paper feed tray 31 that stores the paper S and a paper supply mechanism 32 that feeds the paper S from the paper feed tray 31. The sheets S in the sheet feed tray 31 are separated one by one by the sheet supply mechanism 32 and supplied toward the process cartridge 5 (between the photosensitive drum 61 and the transfer roller 63).

  The exposure apparatus 4 is disposed in the upper part of the main body housing 2 and includes a laser light emitting unit (not shown), a polygon mirror, a lens, a reflecting mirror, and the like that are not shown. In this exposure device 4, the surface of the photosensitive drum 61 is exposed by scanning the surface of the photosensitive drum 61 at high speed with laser light (see the chain line) based on the image data emitted from the laser light emitting unit.

  The process cartridge 5 is disposed below the exposure apparatus 4 and is detachably (replaceable) attached to the main body housing 2 through an opening 2A formed when the cover 21 provided on the main body housing 2 is opened. It has a configuration. The process cartridge 5 includes a drum unit 6 and a developing cartridge 7 as an example of the cartridge.

  The developing cartridge 7 is detachable from the drum unit 6, and is configured to be replaceably attached to the main body housing 2 while being attached to the drum unit 6. The developing cartridge 7 mainly includes a developing roller 71, a supply roller 72, a layer thickness regulating blade 73, a toner accommodating portion 74 that accommodates toner (developer), and an agitator 75 as an example of a stirring member. ing.

  In the developing cartridge 7, the toner in the toner accommodating portion 74 is conveyed (supplied) toward the supply roller 72 while being agitated by the rotating agitator 75, and then supplied as the developing roller 71 and the supply roller 72 rotate. Supplied from the roller 72 to the developing roller 71. The toner supplied onto the developing roller 71 enters between the layer thickness regulating blade 73 and the developing roller 71 as the developing roller 71 rotates, and is carried on the developing roller 71 as a thin layer having a constant thickness. The

  The drum unit 6 mainly includes a photosensitive drum 61, a charger 62, and a transfer roller 63. In the drum unit 6, the surface of the photosensitive drum 61 is uniformly charged by the charger 62, and then exposed by the laser beam from the exposure device 4, whereby the electrostatic latent image is formed on the surface of the photosensitive drum 61. Is formed.

  Then, the toner carried on the developing roller 71 is supplied to the electrostatic latent image formed on the surface of the photosensitive drum 61, whereby a toner image is formed on the surface of the photosensitive drum 61. Thereafter, the sheet S is conveyed between the photosensitive drum 61 and the transfer roller 63, whereby the toner image formed on the surface of the photosensitive drum 61 is transferred onto the sheet S.

  The fixing device 8 is disposed behind the process cartridge 5, and mainly includes a heating roller 81 and a pressure roller 82 disposed so as to face the heating roller 81 and press the heating roller 81. In the fixing device 8, the toner image transferred onto the paper S is thermally fixed while the paper S passes between the heating roller 81 and the pressure roller 82. The paper S on which the toner image is thermally fixed (image is formed) is discharged onto the paper discharge tray 22 by the paper discharge roller 23.

<Detailed configuration of laser printer>
Next, the detailed configuration and operation of Le Zapurinta 1 for (control) will be described. In the following description, the configuration of the developing cartridge 7 and the main body housing 2 related to the present invention will be described and then the control in the laser printer 1 will be described.

(Developer cartridge configuration)
2A and 2B, the developing cartridge 7 includes a gear mechanism 76 in addition to the developing roller 71, the toner containing portion 74, the agitator 75, and the like.
A pair of transparent light transmitting portions 74A facing in the left-right direction are provided on the left and right side walls (not shown) of the toner containing portion 74 (see also FIG. 3).

  The agitator 75 includes a rotary shaft 75A rotatably supported on the left and right side walls of the toner storage portion 74, a flexible sheet member 75B that stirs and conveys the toner T in the toner storage portion 74 during rotation, and a light when rotated. The wiper 75C mainly wipes off the toner T adhering to the transmission part 74A.

  The gear mechanism 76 is a mechanism for transmitting the driving force input from the laser printer 1 to the developing roller 71, the supply roller 72 and the agitator 75, and is provided on the left side surface of the developing cartridge 7. The gear mechanism 76 mainly includes an input gear 76A to which driving force is input, a developing roller gear 76B and a supply roller gear 76C that mesh with the input gear 76A, and an agitator gear 76E that meshes with the input gear 76A via an intermediate gear 76D. Has been.

  The developing roller gear 76B, the supply roller gear 76C, and the agitator gear 76E are gears that rotate and drive the developing roller 71, the supply roller 72, and the agitator 75, respectively. Are integrally provided. With such a gear mechanism 76, the developing roller 71 and the agitator 75 rotate together in the developing cartridge 7 when a driving force is input to the input gear 76 </ b> A.

(Configuration of the main unit casing)
As shown in FIG. 3, the laser printer 1 includes a motor M serving as a drive source, a light emitting element 91, a light receiving element 92, and a control device 100 that controls the operation of the laser printer 1 in the main body housing 2. I have.

  The driving force of the motor M is input to the gear mechanism 76 (input gear 76A) of the developing cartridge 7 by a known driving force transmission mechanism (not shown) and transmitted to the developing roller 71, the agitator 75, and the like.

  The light emitting element 91 and the light receiving element 92 are arranged to face each other so as to sandwich the pair of light transmitting portions 74 </ b> A of the developing cartridge 7 attached to the main body housing 2. As such a light emitting element 91 and a light receiving element 92, for example, a known optical sensor can be adopted. Light emitted from the light emitting element 91 (see the broken line) passes through one light transmitting portion 74A and enters the developing cartridge 7 (toner accommodating portion 74), and is received by the light receiving element 92 through the other light transmitting portion 74A. Is done.

  The light receiving element 92 is an element whose output voltage value (output value) changes according to the amount of received light (the intensity of the received light), and receives the light to generate a light receiving signal as shown in FIG. To (determination means 110). In the present embodiment, a light receiving element 92 is used that has a small output voltage value when the intensity of received light is small and a large output voltage value when the intensity of received light is large.

  2A, when the amount of toner T in the developing cartridge 7 is large, the light entering the developing cartridge 7 is blocked by the toner T. Almost no light is received. The light reception signal as shown in FIG. 4 is obtained after the amount of toner T in the developing cartridge 7 is reduced to some extent.

  Returning to FIG. 3, the control device 100 includes a CPU, a RAM, a ROM, an input / output interface (not shown), and the like, and controls each unit of the laser printer 1 according to a preset program. The control device 100 mainly includes a determination unit 110 and a drive control unit 120 as functional units related to the present invention.

  The determination unit 110 has a function of determining the replacement timing of the developing cartridge 7 based on the light reception signal output from the light receiving element 92. In the present embodiment, the replacement timing of the developing cartridge 7 is determined when the agitator 75 rotates continuously when the agitator 75 rotates more than a predetermined number of times (in this embodiment, two rotations as an example). This is executed after the third rotation after starting.

  Here, the time when the agitator 75 is continuously rotated more than a predetermined number of times (two rotations) is when the agitator 75 is continuously rotating more than two times. Specifically, a print job with a large number of prints in one image forming operation (for example, a print job for forming an image on two or more sheets S in one image forming operation) (hereinafter referred to as a continuous print job) .) Is input, and when the image forming operation is executed based on this continuous print job, or when a count value C described later exceeds a predetermined value ThC, an operation of continuously rotating the agitator 75 is executed. Time (see FIG. 4A).

  The determination of the replacement timing of the developing cartridge 7 in the determination unit 110 will be described with reference to FIG. 4A. First, the determination unit 110 starts the third rotation after the agitator 75 starts rotating (this embodiment). In step S4, the time when the output voltage value based on the amount of light received by the light receiving element 92 exceeds a preset light receiving reference value V1 is calculated. Next, the determination unit 110 calculates a ratio (determination target value R) of the time during which the output voltage value exceeds the light reception reference value V1 in one cycle of the fourth rotation.

  Then, the determination unit 110 determines whether or not the determination target value R exceeds a predetermined ratio (determination threshold ThR) (R> ThR?), And the determination target value R exceeds the determination threshold ThR. In this case, it is determined that it is time to replace the developing cartridge 7. For example, if the determination threshold value ThR is set to 10%, when the determination target value R is 11%, the determination target value R exceeds the determination threshold value ThR. It is determined that the developing cartridge 7 that has been replaced is time to replace.

  When it is determined that the developing cartridge 7 is to be replaced, the determination unit 110 displays on the display provided in the laser printer 1 that it is the replacement time or sounds an alarm sound to the user. Informs that it is time to replace.

  By the way, the determination unit 110 may reduce the accuracy of the determination when the operation of rotating the agitator 75 by two rotations or less (the first and second rotations in FIG. 4) is performed. Do not judge the replacement time. Therefore, if the operation of rotating the agitator 75 twice or less is executed continuously (if the determination unit 110 does not have a function described later), the replacement timing of the developing cartridge 7 is not determined for a while. A situation may arise.

  Therefore, in the present embodiment, the determination unit 110 counts an index value serving as an index of the usage amount of the toner T while the operation in which the agitator 75 rotates twice (predetermined number of times) continues, and the count value C When the predetermined value ThC exceeds a predetermined value ThC, that is, when it is estimated that a fixed amount of toner T in the developing cartridge 7 has been used, the replacement timing of the developing cartridge 7 is determined.

  Specifically, first, the determination unit 110 continuously performs a print job (hereinafter referred to as a single-sheet print job) that is sufficient if the agitator 75 is rotated twice (a predetermined number of times or less) to complete the image forming operation. In this case, the number of inputs (continuous input count) of a single print job as an example of the index value is counted. Here, the single-sheet print job is a print job in which the number of rotations of the agitator 75 during the image forming operation is two because the number of printed sheets in one image forming operation is small (because it is one). It shall be said.

  Then, when the number of inputs (count value C) of the single-sheet print job exceeds a predetermined value ThC (for example, 10), the determination unit 110 rotates the agitator 75 continuously for more than two rotations (predetermined number). To determine the replacement time. More specifically, as shown in FIG. 4A, when the count value C exceeds a predetermined value ThC (C> ThC), the determination unit 110 forms an image based on the last input print job. After the operation is completed (after the agitator 75 has rotated twice), the agitator 75 is continuously rotated (two more rotations) via the drive control means 120 without stopping, and the determination target value R is set to the fourth rotation from the rotation start. It is calculated, and it is determined whether or not the calculated determination target value R exceeds the determination threshold ThR (R> ThR?).

  In addition, when the agitator 75 continuously rotates more than two rotations (predetermined number of times), the determination unit 110 is more specifically determined to rotate before exceeding two rotations (more than two rotations). The count value C is reset at any time during the rotation exceeding 2 rotations and after the rotation exceeding 2 rotations.

  Specifically, the count value C is predetermined when a continuous print job is input in the middle of counting the number of continuous inputs of a single print job, or during or after execution of an image forming operation based on the continuous print job. If the count value C exceeds the predetermined value ThC, the determination means is at any time such as during or after the agitator 75 is continuously rotated over two rotations because the count value C exceeds the predetermined value ThC. 110 resets the count value C. In such a case, since the replacement time is determined, the situation in which the replacement time is not determined for a while is eliminated.

  As shown in FIG. 4B, when the count value C does not exceed the predetermined value ThC (C ≦ ThC), the determination unit 110 performs an image forming operation based on the currently input single-sheet print job. Upon completion (end), the rotation of the agitator 75 is stopped via the drive control means 120. At this time, the agitator 75 rotates twice from the start of rotation and stops.

  The drive control means 120 controls the drive (ON / OFF, rotation speed, etc.) of the motor M, thereby driving the drive force transmission mechanism (not shown) provided in the laser printer 1 and the gear mechanism 76 of the developing cartridge 7. The agitator 75 has a function of controlling driving (rotation / stop) and the number of rotations. For example, when the agitator 75 is rotated four times, the drive control unit 120 drives the motor M for the time for which the agitator 75 is rotated four times (turns ON), and when the agitator 75 is stopped, the drive control unit 120 Stop (turn off).

(Control in laser printer)
The flow of control in the laser printer 1 will be described with reference to the flowchart shown in FIG.
As shown in FIG. 5, when a print job is input (START), the control device 100 executes an image forming operation based on the input print job, and the input print job is a single-sheet print job. It is determined whether or not (S10).

  When the input print job is a single-sheet print job (S10, Yes), the control device 100 counts up the count value C (the number of continuous inputs of the single-sheet print job) (sets as C + 1) (S20). In addition, it is determined whether or not the count value C exceeds a predetermined value ThC (S30).

  When the count value C does not exceed the predetermined value ThC (S30, No), the control device 100 ends the process upon completion of the image forming operation (END). On the other hand, when the count value C exceeds the predetermined value ThC (S30, Yes), the control device 100 resets the count value C to 0 (S40) and continues the agitator 75 after the image forming operation is completed. The determination target value R is calculated by rotation, and it is determined whether or not the calculated determination target value R has exceeded the determination threshold ThR (development timing of the developing cartridge 7) (S50).

  In step S10, when the input print job is not a single-sheet print job (in the case of a continuous print job) (S10, No), the control device 100 resets the count value C (S40) and performs continuous printing. The replacement timing of the developing cartridge 7 is determined during the image forming operation based on the job (S50).

  When the toner T is sufficiently left in the developing cartridge 7 (when it is not the replacement time), the determination target value R does not exceed the determination threshold ThR in step S50 (S50, No), and thus the control device 100 performs the process. End (when an image forming operation based on a continuous print job is being executed, the processing ends upon completion of the image forming operation) (END).

  On the other hand, when the amount of toner T in the developing cartridge 7 becomes small (it is time for replacement), the determination target value R exceeds the determination threshold ThR in step S50 (S50, Yes). The development cartridge 7 is notified that it is time to replace it (S60), and the process is terminated (END).

According to the above, the following effects can be obtained in the present embodiment.
The determination unit 110 counts the number of times the single print job is input while the single print job is continuously input. When the count value C exceeds the predetermined value ThC, the determination unit 110 determines the replacement timing of the developing cartridge 7. Therefore, for example, after completion of the image forming operation based on the single-sheet print job, the total number of rotations of the agitator 75 is compared with the case where the replacement time is determined by rotating the agitator 75 more than two times each time. Can be reduced.

  Thereby, since the total number of rotations of the agitator 75 and the developing roller 71 configured to rotate with the agitator 75 can be reduced, a decrease in charging performance of the toner T can be suppressed. As a result, the life of the developing cartridge 7 can be extended. In addition, since the initial capacity of the toner T accommodated in the developing cartridge 7 can be reduced while ensuring the same life as the conventional one, the developing cartridge 7 and the laser printer 1 can be downsized.

  Also, the replacement timing of the developing cartridge 7 is determined by rotating the agitator 75 continuously over a predetermined number of times to sufficiently disperse the toner T in the developing cartridge 7, and the light receiving signal of the light receiving element 92 is stabilized. Since this is performed later, the replacement time can be determined with higher accuracy than when the replacement time is determined at the initial rotation of the agitator 75 (the first and second rotations in FIG. 4).

  In the present embodiment, the determination unit 110 resets the count value C when the agitator 75 continuously rotates more than two rotations, so that the determination of the replacement time is continuously performed unnecessarily. Can be prevented. As a result, the total number of rotations of the agitator 75 and the developing roller 71 can be further reduced, so that a decrease in charging performance of the toner T can be further suppressed.

  In the present exemplary embodiment, the number of times of input of a single print job is exemplified as an index value serving as an index of the usage amount of the toner T (developer). However, the present invention is not limited to this. For example, when a means for counting the number of dots (pixels) of an image transferred to the paper S (recording sheet) is provided, the index value may be the number of dots printed on the paper S. Further, when a means for counting the number of printed sheets S is provided, the index value may be the number of printed sheets S.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the following description, the same components as those of the above-described embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In addition, a white arrow in FIG. 6 (and FIG. 7) referred to in the following description indicates that the agitator 75 is rotating. An arrow containing the characters “single print job” or “continuous print job” indicates that the agitator 75 is rotating based on the image forming operation, and the other arrows are particularly the replacement time. This indicates that the agitator 75 is rotating.

  In the first embodiment, when the count value C exceeds the predetermined value ThC, the determination unit 110 continues to rotate without stopping the agitator 75 after completion of the image forming operation based on the last input single-sheet print job. Thus, the replacement timing of the developing cartridge 7 is determined. However, there is a possibility that the control for continuously rotating the agitator 75 may not be easy (the control is not in time) due to the speeding up of the image forming operation.

  Therefore, when the count value C exceeds the predetermined value ThC, the determination unit 110 of the present embodiment rotates the agitator 75 continuously for more than two rotations (predetermined number of times) when the next print job is input. To determine the replacement time.

  More specifically, as shown in FIGS. 6A and 6B, when the count value C exceeds a predetermined value ThC (C> ThC), the determination unit 110 determines the currently input single-sheet print job. The rotation of the agitator 75 is temporarily stopped upon completion of the image forming operation based on (time t1), and when the next print job is input, the replacement time (R> ThR?) Is determined.

  As shown in FIG. 6A, when the next continuous print job is input, the agitator 75 continuously rotates more than two rotations, so that an image forming operation based on the continuous print job is performed as usual. Also determine the replacement time. Also, as shown in FIG. 6B, when a single print job is input next, the agitator 75 is stopped after the image forming operation based on the single print job is completed (after time t2). Then, the rotation time is continuously rotated up to four times (see also FIG. 4A) to determine the replacement time.

[Third Embodiment]
Next, a third embodiment as a reference form will be described.
When the count value C exceeds the predetermined value ThC, the determination unit 110 according to the present embodiment continuously exceeds the predetermined number of times after completion of the image forming operation based on the last inputted single-sheet print job. Then, a determination operation is performed to determine the replacement time by rotating the rotation (for example, four rotations).

  More specifically, as shown in FIG. 7, when the count value C exceeds the predetermined value ThC (C> ThC), the determination unit 110 completes the image forming operation based on the currently input single-sheet print job. Thus, the rotation of the agitator 75 is temporarily stopped (the operation is ended). Then, for example, the agitator 75 in a stopped state is continuously rotated four times, and a determination operation for determining the replacement time (R> ThR?) At the fourth rotation is executed.

According to the second and third embodiments described above, even when the speed of image forming operation in the laser printer 1 is increased, the replacement time is accurately determined while suppressing a decrease in toner charging performance. it is Ru can. Conversely, by adopting the second embodiment and the third embodiment, it is possible to increase the speed of the image forming operation.

[Fourth Embodiment]
Next, a fourth embodiment as a reference form will be described.
In the first to third embodiments, the replacement timing of the developing cartridge 7 is determined when a single print job is continuously input a fixed number of times (the number of times the count value C exceeds the predetermined value ThC). . In other words, this is the same as determining the replacement time at certain intervals (although it is indefinite). In the present embodiment, the replacement time is determined at regular intervals (predetermined intervals).

  That is, the determination unit 110 of this embodiment determines the replacement timing of the developing cartridge 7 by rotating the agitator 75 continuously over a predetermined number of times (for example, four rotations) at predetermined intervals. Here, the predetermined interval is an interval (time) longer than the time during which the agitator 75 rotates twice (rotates a predetermined number of times).

  More specifically, as shown in FIG. 8, the determination unit 110 is turned on when the laser printer 1 is turned on, when the cover 21 is closed, or when the image forming operation based on the last print job is completed. The time t is counted from when the replacement time is finally determined (START), and whether or not a predetermined time Tht (for example, 6 hours) longer than the time for which the agitator 75 rotates twice has elapsed (t> Tht?) Is determined (S11).

  When the predetermined time Tht has elapsed (S11, Yes), the determination unit 110 resets the counted time t (sets to t = 0) (S12), and the agitator 75 in the stopped state, for example, continuously Then, it is rotated four times to determine the replacement time (R> ThR?) (S50).

  If it is determined that it is not the replacement time (S50, No), the determination unit 110 ends the processing (END) and restarts the counting of the time t (returns to START). On the other hand, when it is determined that it is the replacement time (S50, Yes), the determination unit 110 notifies the user that it is the replacement time (S60), and ends the processing (END).

  Also in the present embodiment described above, the determination unit 110 determines the replacement timing of the developing cartridge every predetermined time Tht (predetermined interval) longer than the time for which the agitator 75 rotates twice. Each time after the formation operation is completed, the total number of rotations of the agitator 75 and the developing roller 71 can be reduced as compared with the case where the replacement time is determined by rotating the agitator 75 more than twice. As a result, a decrease in charging performance of the toner T can be suppressed. Further, since the determination of the replacement time is performed after the agitator 75 is continuously rotated more than two times (predetermined number of times), the replacement time can be accurately determined.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. About a concrete structure, it can change suitably in the range which does not deviate from the meaning of this invention.

  Specific values such as the predetermined number of times and the continuous input number of print jobs in the embodiment are examples, and the present invention is not limited to the embodiment. That is, for example, the predetermined number of times (the number of times until the output value of the light receiving element is stabilized) varies depending on the volume of the cartridge (the amount of developer that can be accommodated), the rotational speed of the stirring member, and the like.

  In the above embodiment, the determination target value is calculated at the fourth rotation after the agitator 75 starts rotating, and when the determination target value exceeds the determination threshold, it is determined that the replacement time is reached. It is not limited to. For example, the determination target value may be calculated at the third rotation or for each rotation after the start of the third rotation. Further, the determination target value may be calculated as a ratio of the time during which the output value of the light receiving element exceeds the light receiving reference value V1 (see FIG. 4A) in a certain time including a plurality of cycles. Further, when the output value of the light receiving element exceeds the light receiving reference value V1, it may be determined that it is the replacement time (in this case, the light receiving reference value V1 corresponds to a determination threshold value).

  The specific configuration of the agitator 75 (stirring member) in the embodiment is merely an example, and the present invention is not limited to the configuration of the embodiment. For example, the stirring member may be configured to include a plurality of flexible sheet members in the rotation direction, or may be configured to include a light shielding member as described in Patent Document 1.

  In the above embodiment, the light receiving element 92 is employed in which the output voltage value is small when the intensity of the received light is small and the output voltage value is large when the intensity of the received light is large. However, the present invention is not limited to this. Is not to be done. For example, a light receiving element may be employed in which the output voltage value increases when the intensity of received light is small and the output voltage value decreases when the intensity of received light is large.

  In the above-described embodiment, the developing cartridge 7 (cartridge) is configured to be replaceable with respect to the main body housing 2 in a state where it is mounted on the drum unit 6 (state of the process cartridge 5), but the present invention is not limited to this. It is not something. For example, the cartridge may be configured to be directly replaceable with respect to the main body housing.

  In the above embodiment, the developing cartridge 7 is exemplified as the cartridge. However, the present invention is not limited to this, and for example, a process cartridge in which the drum unit 6 and the developing cartridge 7 of the above embodiment are integrally formed (cannot be attached or detached). There may be.

  In the above-described embodiment, the laser printer 1 is exemplified as the image forming apparatus. However, the present invention is not limited to this, and may be, for example, an LED printer that exposes a photoconductor with arranged LEDs. The image forming apparatus is not limited to a printer, and may be, for example, a copier or a multi-function machine including a document reading apparatus such as a flat bed scanner.

DESCRIPTION OF SYMBOLS 1 Laser printer 7 Developing cartridge 71 Developing roller 75 Agitator 76 Gear mechanism 91 Light emitting element 92 Light receiving element 110 Determination means C Count value R Determination target value T Toner ThC Predetermined value ThR Determination threshold

Claims (3)

It has a stirring member that stirs the developer by rotating and a developing roller that carries the developer, and is configured such that the stirring member and the developing roller rotate together when a driving force is input. An image forming apparatus configured to optically detect the amount of developer in a replaceable cartridge,
A light emitting element that emits light into the cartridge;
A light receiving element that receives light emitted from the light emitting element and passed through the cartridge;
It is determined whether or not a determination target value based on the amount of light received by the light receiving element exceeds a determination threshold when the stirring member is continuously rotated more than a predetermined number of times, and the determination target value is the determination threshold Determining means for determining that it is time to replace the cartridge when exceeding
The determination means includes
While a print job that is sufficient to rotate the stirring member below the predetermined number of times to complete the image forming operation is continuously input, an index value serving as an index of the amount of developer used is counted.
If the count value exceeds a predetermined value, the stirring member is continuously rotated more than the predetermined number of times when the image forming operation based on the next input print job is performed, and the determination target value is An image forming apparatus that determines whether or not the determination threshold is exceeded.   The image forming apparatus according to claim 1, wherein the determination unit resets the count value when the stirring member continuously rotates more than the predetermined number of times.   The index value includes the number of dots printed on the recording sheet, the number of printed recording sheets, and the number of print job inputs that is sufficient to rotate the stirring member below the predetermined number of times to complete the image forming operation. The image forming apparatus according to claim 1, wherein the image forming apparatus is any one of the above.

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