JP5402961B2 - 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 Determining whether or not a determination target value based on the amount of light received by the light receiving element exceeds a determination threshold, and a light receiving element that receives light emitted from the light emitting element and passed through the cartridge; Determination means for determining that the cartridge is in a replacement time when the determination target value exceeds the determination threshold value, and the determination means rotates the stirring member a predetermined number of times or less to complete the image forming operation. When a sufficient print job is input, it is determined whether or not the determination target value has exceeded a temporary determination threshold while the stirring member rotates the predetermined number of times or less, and the temporary determination threshold is not exceeded. Stops the rotation of the stirring member upon completion of the image forming operation based on the print job, and when the temporary determination threshold is exceeded, the stirring member is continuously rotated more than the predetermined number of times to perform the determination. It is characterized by determining whether the target value 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, when the print job with a small number of prints is input, the determination unit first determines based on the amount of light received by the light receiving element without determining the replacement time of the cartridge. It is determined whether the determination target value has exceeded a provisional determination threshold. If the temporary determination threshold value is not exceeded, the rotation of the stirring member is stopped upon completion of the image forming operation.For example, after the completion of the image forming operation based on the print job with a small number of printed sheets, the stirring member is extra each time. The total number of rotations of the stirring member can be reduced as compared with the case where the replacement time is determined by rotating. 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.

  Further, when the temporary determination threshold is exceeded, it is determined whether the determination target value exceeds the determination threshold by continuously rotating the stirring member more than a predetermined number of times (determining the cartridge replacement time). Compared with the configuration in which the cartridge replacement timing is determined while the stirring member rotates a predetermined number of times or less (the initial rotation of the stirring member), the cartridge replacement timing can be determined with high accuracy.

  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, the figure (a) which shows the case where a judgment target value does not exceed a temporary judgment threshold in temporary judgment, and the case where a judgment target value exceeds a temporary judgment threshold in temporary judgment It is a figure (b) shown. It is a flowchart which shows the control in a laser printer. It is explanatory drawing of the control after the determination target value which concerns on 2nd Embodiment exceeds the temporary determination threshold value, The figure (a) which shows when a continuous print job is input next time, and the one sheet print job next time It is a figure (b) showing when it was inputted. It is explanatory drawing of the control after the determination target value which concerns on 3rd Embodiment exceeds a temporary determination threshold value.

[First Embodiment]
Next, a first embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, first, a schematic configuration of a laser printer 1 as an example of an image forming apparatus will be briefly described, and then a detailed configuration and operation of the laser printer 1 according to a characteristic part of the present invention 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 (control) of the laser printer 1 according to the characteristic part of the present invention 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, a drive control unit 120, and a storage unit 190 as functional units related to the present invention.

  The determination unit 110 has a function of executing a development cartridge replacement time determination (main determination) and a function of determining whether or not to execute the main determination (temporary determination). If the determination unit 110 determines that the development cartridge 7 is in the replacement period in this determination, the determination unit 110 displays on the display provided in the laser printer 1 that it is the replacement period or sounds an alarm sound. The user is informed that it is time to replace the developing cartridge 7.

Hereinafter, the main determination and the temporary determination will be described.
In this determination, when the agitator 75 is continuously rotated more than a predetermined number of times (in this embodiment, two rotations are taken as an example), after the third rotation starts after the agitator 75 starts rotating. To be executed.

  Here, in the present embodiment, when the agitator 75 continuously rotates more than a predetermined number of times (two rotations), an operation in which the agitator 75 continuously rotates more than two rotations is executed. Is the time. 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 the image forming operation is executed based on this continuous print job, or after a tentative determination described later (after the determination target value R exceeds the tentative determination threshold Th1), the agitator 75 is continued. For example, when a rotating operation is being performed (see FIG. 4B).

  In this determination, as shown in FIG. 4B, the determination unit 110 first starts the third rotation after the agitator 75 starts rotating (assumed to be performed in the fourth rotation in this embodiment). The time when the output voltage value based on the amount of light received by the light receiving element 92 exceeds the 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.

  Thereafter, the determination unit 110 determines whether or not the determination target value R exceeds a predetermined ratio (determination threshold Th2) (R> Th2?), And the determination target value R exceeds the determination threshold Th2. In this case, it is determined that it is time to replace the developing cartridge 7. For example, if the determination threshold value Th2 is set to 10%, if the determination target value R is 11%, the determination target value R exceeds the determination threshold value Th2. It is determined that the developing cartridge 7 that has been replaced is time to replace.

  Here, the reason for executing this determination after the start of the third rotation (when continuously rotating over a predetermined number of times) will be described.

  The toner T in the developing cartridge 7 is scattered in the developing cartridge 7 by the rotation of the agitator 75. In particular, when the amount of the toner T decreases as shown by the solid line in FIG. In the initial rotation (the first and second rotations in FIG. 4B), the toner accumulated on the bottom is not sufficiently scattered, so that the incident light easily passes through the developing cartridge 7 and the light receiving element 92. The output voltage value increases.

  On the other hand, in the developing cartridge 7 of the present embodiment, after the third rotation after the agitator 75 starts rotating, the toner T is scattered almost uniformly in the developing cartridge 7, and therefore the output of the light receiving element 92. The voltage value (light reception signal) shows a stable waveform. In other words, in this embodiment, two rotations (predetermined number of times) are the number of rotations of the agitator 75 until the output voltage value of the light receiving element 92 is stabilized.

  Based on the above, if the main determination is executed in the first and second rotations, the accuracy of determination of the replacement time may be reduced (determination is made that it is the replacement time even though the toner T still remains). In the embodiment, the determination of the replacement time (main determination) is executed after the start of the third rotation when the output voltage value of the light receiving element 92 is stabilized.

  The provisional determination is executed while the agitator 75 is rotated a predetermined number of times or less when a print job is input in which it is sufficient to rotate the agitator 75 a predetermined number of times or less to complete the image forming operation. Specifically, in the present embodiment, the provisional determination requires a print job in which it is sufficient to rotate the agitator 75 twice to complete the image forming operation (the number of printed sheets in one image forming operation is small (for example, 1 Therefore, when a print job in which the number of rotations of the agitator 75 is two rotations (hereinafter referred to as one sheet print job) is input, the image forming operation is being performed (while the agitator 75 rotates twice). ) Is executed.

  In the tentative determination, as shown in FIGS. 4A and 4B, the determination unit 110 determines the determination target value R at the first rotation (or the second rotation) in the same manner as in the main determination. calculate. Thereafter, the determination unit 110 determines whether or not the determination target value R exceeds a predetermined ratio (provisional determination threshold Th1) that is larger than the determination threshold Th2 described above. For example, if the provisional determination threshold Th1 is set to 20%, when the determination target value R is 19%, it is determined that the determination target value R does not exceed the provisional determination threshold Th1, and the determination target value When R is 21%, it is determined that the determination target value R exceeds the provisional determination threshold Th1.

  As shown in FIG. 4A, when the determination target value R does not exceed the temporary determination threshold Th1 (R ≦ Th1), the determination unit 110 performs an image forming operation based on a single-sheet print job (on one sheet S). When the image forming operation is completed, the rotation of the agitator 75 is stopped via the drive control unit 120. At this time, the agitator 75 rotates twice from the start of rotation and stops.

  On the other hand, as shown in FIG. 4B, when the determination target value R exceeds the provisional determination threshold Th1 (R> Th1), the determination unit 110 stores a flag (temporary determination flag) indicating that fact in the storage unit 190. (F = 1) and the agitator 75 is continuously rotated more than two rotations (predetermined number of times) via the drive control means 120 to execute this determination.

  More specifically, when the determination target value R calculated in the first rotation exceeds the provisional determination threshold value Th1, the determination unit 110 completes the image forming operation based on the single-sheet print job (after the agitator 75 rotates twice). ), The agitator 75 is continuously rotated (two more rotations) without stopping, and a new determination target value R is calculated at the fourth rotation from the start of rotation, and whether or not the calculated determination target value R exceeds the determination threshold Th2 Determine whether.

  In this determination after exceeding the provisional determination threshold Th1, when it is determined that the developing cartridge 7 is in the replacement time, the determining unit 110 notifies the user that the developing cartridge 7 is in the replacement time.

  Further, in the main determination after exceeding the temporary determination threshold Th1, when it is determined that the developing cartridge 7 is not at the replacement time, the determination unit 110 thereafter performs the main determination at predetermined intervals (the determination target value R is equal to the determination target value R). It is determined whether or not the determination threshold Th2 has been exceeded).

  More specifically, after the determination target value R exceeds the temporary determination threshold Th1 (when the temporary determination flag is set (when F = 1)), the determination unit 110 continuously inputs a single print job. During this time, an index value (for example, the number of continuous inputs of a single print job) that is an index of the amount of toner T used is counted. When the count value (number of continuous inputs) exceeds a predetermined value (for example, 10), the determination unit 110 determines that the determination target value R exceeds the temporary determination threshold Th1 in the temporary determination (FIG. 4B). As in the case of the reference), the agitator 75 is continuously rotated more than two times (predetermined number of times), and this determination is executed.

  In this main determination, when it is determined that the developing cartridge 7 is the replacement time, the determination unit 110 notifies the user that the developing cartridge 7 is the replacement time, and when it is determined that the developing cartridge 7 is not the replacement time, The determination unit 110 again counts the number of continuous inputs of the single print job while the single print job is continuously input.

  Note that the determination unit 110 resets the count value when the agitator 75 continuously rotates more than two revolutions (when the agitator 75 continuously rotates more than two revolutions). More specifically, the determination unit 110 is configured to input a continuous print job while counting the number of continuous inputs of a single print job and execute an image forming operation based on the continuous print job. When the value exceeds the predetermined value, the count value is reset when the agitator 75 is continuously rotated more than two times. This is because this determination is performed in such a case.

  In addition, when the developing cartridge 7 is replaced with a new one, the determining unit 110 resets the temporary determination flag (F = 0).

  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 (S1).

  If the input print job is not a single-sheet print job (if it is a continuous print job) (S1, No), the control device 100 executes this determination during the image forming operation (the fourth rotation of the agitator 75). (S2). When the input print job is a single-sheet print job (S1, Yes), the control device 100 determines whether or not a temporary determination flag is set (whether F = 1) (S3). ).

  Here, when the amount of toner T in the developing cartridge 7 is large, the determination target value R does not exceed the determination threshold Th2 in this determination (S2) (S2, No), so the control device 100 completes the image forming operation. Thus, the process ends (END).

  Further, when the amount of toner T in the developing cartridge 7 is large and the temporary determination flag is not set (when F = 0) (S3, No), the control device 100 is performing an image forming operation (1 of the agitator 75). Temporary determination is executed at (rotation) (S4). When the amount of toner T is large, the determination target value R does not exceed the temporary determination threshold Th1 even in the temporary determination (S4, No), and thus the control device 100 stops the rotation of the agitator 75 upon completion of the image forming operation. Then, the process is terminated (END).

  When the amount of toner T in the developing cartridge 7 decreases to some extent, the determination target value R exceeds the temporary determination threshold Th1 in the temporary determination (S4) (S4, Yes). In this case, the control device 100 sets a temporary determination flag (F = 1) (S6) and, after the image forming operation is completed, continuously rotates the agitator 75 to execute the main determination (S2). When the determination target value R does not exceed the determination threshold Th2 (S2, No), the control device 100 stops the rotation of the agitator 75 and ends the processing (END).

  Even after the determination target value R exceeds the temporary determination threshold Th1 in the temporary determination (when the temporary determination flag is set), when the print job is input (START), the control device 100 first performs the image forming operation. And whether or not the input print job is a single-sheet print job is determined (S1).

  When the input print job is a single-sheet print job (S1, Yes), the control device 100 determines whether or not a temporary determination flag is set (whether F = 1) (S3). Here, since the temporary determination flag is set (F = 1) (S3, Yes), the control device 100 counts up the count value C (the number of continuous inputs of a single print job) (C + 1). (S7), it is determined whether or not the count value C exceeds a predetermined value ThC (for example, 10) (S8).

  When the count value C does not exceed the predetermined value ThC (S8, No), the control device 100 ends the processing upon completion of the image forming operation (END). On the other hand, when the count value C exceeds the predetermined value ThC (S8, Yes), the control device 100 resets the count value C to 0 (S9) and continues the agitator 75 after the image forming operation is completed. The main determination is performed by rotating (S2). In this main determination, when the determination target value R does not exceed the determination threshold Th2 (S2, No), the control device 100 stops the rotation of the agitator 75 and ends the processing (END).

  In step S1, if the input print job is a continuous print job (S1, No), the control device 100 resets the count value C (S9) and executes this determination during the image forming operation (S2). .

  When the amount of toner T in the developing cartridge 7 becomes small (the replacement time is reached), the determination target value R exceeds the determination threshold Th2 (S2, Yes) in the main determination (S2), so the control device 100 The user is notified that it is time to replace the developing cartridge 7 (S10), and the process is terminated (END).

According to the above, the following effects can be obtained in the present embodiment.
When the single print job is input, the determination unit 110 first performs a temporary determination. If the determination target value R does not exceed the temporary determination threshold Th1, the determination unit 110 rotates the agitator 75 upon completion of the image forming operation. For example, the number of rotations of the agitator 75 is reduced as compared with the case where the replacement time is determined by rotating the agitator 75 more than twice after each completion of the image forming operation based on the single-sheet print job. be able to.

  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.

  When the determination target value R exceeds the provisional determination threshold Th1, the main determination is executed by continuously rotating the agitator 75 over a predetermined number of times, so that the agitator 75 is rotated a predetermined number of times or less (the agitator 75). Compared to the configuration for determining the replacement time of the developing cartridge 7 at the initial stage of the rotation, the replacement time can be determined with high accuracy.

  In the present embodiment, after the determination target value R exceeds the temporary determination threshold Th1, the determination unit 110 stores this (sets a temporary determination flag), and sets a predetermined interval (the number of continuous inputs of a single print job). This determination is performed every time the value exceeds a predetermined value), for example, compared with the case where the determination is executed every time after the provisional determination threshold Th1 is exceeded and after the image forming operation based on the single-sheet print job is completed. The total number of rotations of the agitator 75 and the developing roller 71 can be further reduced.

  Since the predetermined number of times is set to the number of rotations of the agitator 75 until the light receiving signal is stabilized, the developing cartridge is executed by executing this determination when the agitator 75 continuously rotates more than the predetermined number of times. 7 can be accurately determined.

  In the present embodiment, in the tentative determination, after the determination target value R exceeds the tentative determination threshold Th1, the determination unit 110 performs the main determination at predetermined intervals. It is not limited. For example, after the determination target value once exceeds the temporary determination threshold, the temporary determination is executed every time a print job is input, and after the determination target value has accumulated the temporary determination threshold and exceeded several times, You may comprise so that this determination may be performed after exceeding several times continuously.

  In this embodiment, when the determination target value R exceeds the provisional determination threshold Th1 and this determination is executed at predetermined intervals, the number of continuous inputs of a single print job exceeds a predetermined value as the predetermined interval. However, the present invention is not limited to this. For example, in the case where a means for counting the number of dots (number of dots) of the image formed on the paper S (recording sheet) is provided, the predetermined interval is the number of dots formed after the determination target value exceeds the provisional determination threshold value. May exceed the predetermined value. Further, in the case where a means for counting the number of recording sheets printed is provided, the predetermined interval may be set until the number of recording sheets printed after the determination target value exceeds the provisional determination threshold exceeds the predetermined value. Furthermore, the predetermined interval may be every predetermined time after the determination target value exceeds the provisional determination threshold.

  In this embodiment, the determination unit 110 resets the count value when a continuous print job is input while counting the number of continuous inputs of a single-sheet print job. However, the present invention is not limited to this. It is not something. That is, the determination unit may be configured not to reset the count value when a continuous print job is input while the number of continuous inputs of the single-sheet print job is being counted.

[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 determination target value R exceeds the provisional determination threshold Th1, the determination unit 110 performs the main determination by continuously rotating the agitator 75 without stopping after the image forming operation is completed. However, there is a possibility that control for continuously rotating the agitator 75 may not be easy (control may not be in time) due to an increase in the speed of the image forming operation.

  Therefore, when the determination target value R exceeds the temporary determination threshold Th1 in the temporary determination, the determination unit 110 of the present embodiment continuously rotates the agitator 75 twice when the next print job is input ( This determination is performed by rotating beyond a predetermined number of times.

  More specifically, as shown in FIG. 6, when the determination unit 110 executes the temporary determination, the determination unit 110 temporarily stops the rotation of the agitator 75 upon completion of the image forming operation regardless of the determination result (time t1). In the temporary determination, when the determination target value R exceeds the temporary determination threshold Th1 (R> Th1), for example, when the next print job is input, the main determination (R> Th2?) Is performed. Run.

  As shown in FIG. 6A, when the next continuous print job is input, the agitator 75 continuously rotates more than two rotations. Therefore, the image forming operation based on the continuous print job is also performed. To execute this judgment. Further, as shown in FIG. 6B, when a single print job is input next, after the completion of the image forming operation (after time t2), the agitator 75 is not stopped and continues to a total of four times. This determination is executed by rotating (see also FIG. 4B).

  In the above description, an example is shown in which the determination is performed when the next (next) print job is input after the determination target value R exceeds the provisional determination threshold Th1, but the present invention is not limited to this. It is not something. For example, this determination is executed when a print job is input several times after the determination target value R exceeds the temporary determination threshold Th1 and a print job after a predetermined number of times (for example, five times) is input. You may do it.

[Third Embodiment]
Next, a third embodiment of the present invention will be described.
When the determination target value R exceeds the temporary determination threshold Th1 in the temporary determination, the determination unit 110 according to the present embodiment continues the agitator 75 after the image forming operation based on the single-sheet print job is completed (after completion). Then, an operation (determination operation) is performed in which the rotation is performed more than a predetermined number of times (four rotations as an example) and this determination is performed.

  More specifically, as shown in FIG. 7, when the provisional determination is performed, the determination unit 110 temporarily stops the rotation of the agitator 75 upon completion of the image forming operation regardless of the determination result (ends the operation). ). When the determination target value R exceeds the temporary determination threshold Th1 in the temporary determination (R> Th1), the stopped agitator 75 is continuously rotated, for example, four times, and the main determination is performed at the fourth rotation ( R> Th2?) Is performed.

  In the present embodiment, after the determination target value R exceeds the provisional determination threshold Th1, the determination operation may be executed at predetermined intervals (for example, every time a print job is input a predetermined number of times). Good. According to this, the total number of rotations of the agitator 75 and the developing roller 71 can be further reduced.

  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 becomes possible to apply the present invention which can be applied. Conversely, by adopting the second embodiment and the third embodiment, it is possible to increase the speed of the image forming operation.

  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-described embodiment, in this determination, the agitator 75 starts the rotation and calculates the determination target value at the fourth rotation. When the determination target value exceeds the determination threshold, it is determined that it is the replacement time. The present invention is not limited to this. 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. 4) 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 same applies to the provisional determination.

  In the embodiment, the determination unit 110 performs the main determination when the agitator 75 continuously rotates more than two rotations (predetermined number of times) (determination target value based on the amount of light received by the light receiving element 92). R is determined so as to determine whether or not R exceeds the determination threshold value Th2, but the present invention is not limited to this. For example, the determination unit may be configured to execute the main determination together with the temporary determination even when the stirring member rotates only a predetermined number of times or less (in the first embodiment, the first to second rotations). In other words, the determination unit may be configured to execute this determination regardless of the number of rotations of the stirring member. In such a configuration, the determination means of the present invention does not notify the user of the determination result of the main determination when the stirring member rotates only a predetermined number of times or less, and determines the determination result of the temporary determination as described above. Based on the control.

  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 R Determination target value T Toner Th1 Temporary determination threshold Th2 Determination threshold

Claims (9)

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;
Determining means for determining whether or not a determination target value based on the amount of light received by the light receiving element has exceeded a determination threshold, and determining that the cartridge is at a replacement time when the determination target value exceeds the determination threshold; Prepared,
The determination means includes
When a print job is input in which it is sufficient to rotate the stirring member a predetermined number of times or less to complete the image forming operation, the determination target value is a temporary determination threshold value while the stirring member rotates the predetermined number of times or less. To determine whether or not
If the temporary determination threshold is not exceeded, the rotation of the stirring member is stopped upon completion of the image forming operation based on the print job,
When the temporary determination threshold value is exceeded, the stirring member is continuously rotated more than the predetermined number of times to determine whether or not the determination target value exceeds the determination threshold value. .   When the determination target value exceeds the provisional determination threshold, the determination unit continues to rotate the stirring member after completion of the image forming operation based on the print job, and the determination target value exceeds the determination threshold. The image forming apparatus according to claim 1, wherein it is determined whether or not the image forming apparatus has been used.   If the determination target value exceeds the provisional determination threshold, the determination unit continuously rotates the stirring member more than the predetermined number of times when a print job is input after the next time. 2. The image forming apparatus according to claim 1, wherein it is determined whether or not a value exceeds the determination threshold value.   When the determination target value exceeds the temporary determination threshold, the determination unit continuously rotates the stirring member more than the predetermined number of times after completion of the image forming operation based on the print job. The image forming apparatus according to claim 1, wherein a determination operation for determining whether a target value exceeds the determination threshold is executed. After the determination target value exceeds the provisional determination threshold, the determination unit has a predetermined number of continuous print job inputs that is sufficient to rotate the stirring member a predetermined number of times or less to complete the image forming operation. the image forming apparatus according to any one of claims 1 to 4 in which the determination target value each time exceeds the value and judging whether exceeds the determination threshold. After the determination target value exceeds the provisional determination threshold, the determination means determines the determination target value every time the number of dots formed after the determination target value exceeds the provisional determination threshold exceeds a predetermined value. 5. The image forming apparatus according to claim 1, wherein the image forming apparatus determines whether or not the threshold value exceeds the determination threshold value. 6. After the determination target value exceeds the provisional determination threshold, the determination unit performs the determination every time the number of printed recording sheets printed after the determination target value exceeds the provisional determination threshold exceeds a predetermined value. The image forming apparatus according to claim 1, wherein a determination is made as to whether or not a target value exceeds the determination threshold value. The determination means determines whether or not the determination target value exceeds the determination threshold every predetermined time after the determination target value exceeds the provisional determination threshold. Item 5. The image forming apparatus according to any one of Items 4 to 5. Wherein the predetermined number of times, the image forming apparatus according to any one of claims 1 to 8 in which the output value of the light receiving element is characterized by a number of to stabilize.

Images