Image forming apparatus

Abstract

To improve throughput in stopping an image forming operation and performing a developer disposal operation.SOLUTION: An image forming apparatus comprises: an internal temperature measuring unit that measures internal temperature; an image formation control unit 136 that controls an image forming operation on the basis of an image forming job, calculates a disposal amount of developer to be disposed of for every predetermined image forming unit according to the ratio of a developer image to a recording medium, and when a cumulative disposal amount, which is an accumulated disposal amount, becomes equal to or more than a predetermined disposal threshold, causes an image forming unit to execute a developer disposal operation of disposing of the developer at a predetermined timing; and an internal temperature control unit 144 that, when the internal temperature becomes equal to or more than a predetermined operation stop threshold, causes the image forming unit to stop the image forming operation. When a predetermined condition is satisfied, the image formation control unit 136 causes the image forming unit to execute the developer disposal operation while the image forming operation is stopped.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an image forming apparatus. [Background technology]

[0002] In recent electrophotographic printers, there is a demand for a smaller footprint when the device is installed, due to environmental considerations and market demands, etc. Furthermore, to save power, low-melting-point toner that can be fixed at low temperatures is being used. However, these devices have a high internal density, which makes the airflow inside the device poor and prone to high temperatures.

[0003] On the other hand, when electrophotographic printers perform low-duty printing, charged toner (hereinafter also referred to as "degraded toner") accumulates in the photosensitive drum unit (hereinafter referred to as "ID unit"), resulting in a decline in print quality. For this reason, a toner disposal operation (also referred to as developer disposal operation) is required, as in the device described in Patent Document 1, for example.

[0004] Furthermore, when performing continuous printing with conventional devices, the temperature inside the device rises, causing the toner in the ID unit or the toner in the waste toner collection mechanism to rise to its melting point and become solidified. For this reason, conventional devices measure the temperature inside the device and control the fan cooling, intermittent printing, or printing pauses to stop image formation operations so that the temperature does not rise above a certain level, preventing the toner from melting and becoming solidified. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-181270 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, the conventional technology has a problem in that the total image forming throughput decreases due to the stop of the image forming operation and the developer disposal operation.

[0007] Therefore, one or more aspects of the present disclosure aim to improve throughput when stopping an image forming operation and performing a developer disposal operation. [Means for solving the problem]

[0008] An image forming apparatus according to one aspect of the present disclosure includes an image forming unit that forms a developer image using a developer, an internal temperature measurement unit that measures the temperature of a predetermined location as an internal temperature, an image forming control unit that controls the image forming operation that forms the developer image based on an image formation job, and calculates the amount of developer to be discarded for each predetermined image forming unit in accordance with the ratio of the developer image to the recording medium, and when the accumulated amount of the discarded amounts becomes greater than a predetermined discard threshold, causes the image forming unit to execute a developer discarding operation to discard the developer at a predetermined timing, and an internal temperature control unit that causes the image forming unit to stop the image forming operation when the internal temperature becomes greater than a predetermined operation stop threshold, and is characterized in that when a predetermined condition is met, the image forming control unit executes the developer discarding operation during the period when the stop is being performed, rather than at the predetermined timing, and the image forming unit discards the developer used for the developer image in the developer discarding operation. [Effects of the Invention]

[0009] According to one or more aspects of the present disclosure, throughput can be improved even when an image forming operation is stopped and a developer disposal operation is performed. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view schematically illustrating a configuration of a main part of an image forming apparatus according to an embodiment. [Figure 2]FIG. 2 is a block diagram illustrating a schematic configuration of a control system of the image forming apparatus according to the embodiment. [Figure 3] FIG. 10 is a schematic diagram illustrating an example of a toner disposal pattern. [Figure 4] FIG. 10 is a schematic diagram for explaining an example of calculating an increasing gradient. [Figure 5] 10(A) and 10(B) are schematic diagrams for explaining an example of calculating a temperature gradient. [Figure 6] 10A and 10B are block diagrams showing an example of a hardware configuration. [Figure 7] 5 is a flowchart showing a first operation of the image forming apparatus according to the embodiment. [Figure 8] 10 is a flowchart showing a second operation of the image forming apparatus according to the embodiment. [Figure 9] 10 is a flowchart showing a third operation of the image forming apparatus according to the embodiment. [Figure 10] 10 is a time chart for explaining an outline of a toner disposal operation. [Figure 11] 10 is a time chart for explaining an outline of stopping a printing operation. [Figure 12] 10 is a time chart for explaining an example in which a toner disposal operation is delayed. [Figure 13] 10 is a time chart for explaining an example in which a toner disposal operation is carried out ahead of schedule. DETAILED DESCRIPTION OF THE INVENTION

[0011] FIG. 1 is a cross-sectional view schematically showing the configuration of a main part of an image forming apparatus 100 according to an embodiment. The medium storage tray 101 stores paper sheets as recording media. A pickup roller 102 picks up a sheet of paper from the media storage tray 101 . The tray hopping rollers 103A and 103B rotate to send a sheet of paper picked up by the pickup roller 102 forward and transport it.

[0012] The ID unit 104 is an image forming section that uses toner as a developer to form a toner image as a developer image. The ID unit 104 includes a photosensitive drum 105 , a charging roller 106 , a supply roller 107 , a developing roller 108 , a cleaning blade 109 , and a waste toner collection container 110 .

[0013] The photosensitive drum 105 is an image carrier that carries an image. The charging roller 106 is a charging unit that applies a negative voltage to the photosensitive drum 105 to uniformly charge the photosensitive drum 105 . Above the photosensitive drum 105, an LED (Light Emitting Diode) head 111 serving as an exposure unit is provided adjacent to the photosensitive drum 105. The LED head 111 is an exposure unit that turns on or off each LED element to irradiate the photosensitive drum 105, to which a negative voltage is applied, with LED light, thereby forming an electrostatic latent image.

[0014] By applying a negative voltage to the supply roller 107 as a supply unit and the development roller 108 as a development unit to the electrostatic latent image formed as described above, toner supplied from the toner cartridge 112 is applied to the photosensitive drum 105. As a result, a toner image is formed on the photosensitive drum 105.

[0015] The toner image formed on the photosensitive drum 105 is transferred onto a sheet of paper being conveyed by a transfer roller 113 with a positive voltage. The transfer roller 113 is a transfer unit that transfers the toner image onto a sheet of paper.

[0016] Residual toner remaining on the photosensitive drum 105 is scraped off by a cleaning blade 109 and collected in a waste toner collection container 110 . During a printing operation or a toner disposal operation (to be described later), residual toner and waste toner remaining on the photosensitive drum 105 are collected and stored in a waste toner collection container 110.

[0017] The waste toner collection container 110 is integrated with the ID unit 104, and when the waste toner collection container 110 becomes full, the ID unit 104 needs to be replaced. The ID unit 104 also needs to be replaced when the photosensitive drum 105 reaches the end of its life.

[0018] The sheet of paper onto which the toner image has been transferred is sent to a fuser 114 . The fixing device 114 is a fixing unit that fixes the toner image transferred onto a sheet of paper onto that sheet of paper. For example, fuser 114 applies heat and pressure to fix the toner image to the sheet of paper.

[0019] The discharge / duplex switching separator 115 is a separator that switches whether a conveyed sheet of paper is conveyed to the duplex side where double-sided printing is performed, or to the discharge side where the paper is discharged outside the apparatus.

[0020] The environmental temperature and humidity sensor 116 is a sensor that measures the temperature and humidity of the image forming apparatus 100 . The internal temperature sensor 117 is an internal temperature measuring unit that measures the temperature at a predetermined location as the internal temperature. Here, the internal temperature sensor 117 measures the temperature in the vicinity of the ID unit 104. The temperature detected by the internal temperature sensor 117 is used as the internal temperature, which is the temperature inside the image forming apparatus 100.

[0021] A single sheet of paper is transported along the medium transport path by transport rollers 118A to 118V. The position of a single sheet of paper on the media transport path is detected by HOP sensor 119A, IN1 sensor 119B, IN2 sensor 119C, WR sensor 119D, and EXIT sensor 119E. By measuring the detection timing of each of these sensors, the transport status of a single sheet of paper can be detected, and transport delays, paper jams, etc. can be detected.

[0022] FIG. 2 is a block diagram showing a schematic configuration of a control system of image forming apparatus 100 according to the embodiment. The image forming apparatus 100 includes an I / F unit 130, a command decode control unit 131, a main control unit 132, an initial control unit 133, a non-volatile memory control unit 134, a media detection sensor control unit 135, an image forming control unit 136, a paper conveyance control unit 142, a fixing control unit 143, and an internal temperature control unit 144.

[0023] The I / F unit 130 receives commands such as print instructions as image formation instructions and other operation instructions from a higher-level host (not shown). The received commands are provided to a command decode control unit 131. The command decode control unit 131 decodes commands from the I / F unit 130 and notifies the main control unit 132 of the commands one by one.

[0024] The main control unit 132 controls the entire processing in the image forming apparatus 100 . For example, the main control unit 132 instructs any one of the initial control unit 133, nonvolatile memory control unit 134, medium detection sensor control unit 135, image formation control unit 136, paper transport control unit 142, fixing control unit 143, and internal temperature control unit 144 to perform control in response to a command from the I / F unit 130. The main control unit 132 also acquires a status from any one of these units and returns the status from the I / F unit 130 to the upper host.

[0025] The initial control unit 133 controls the initial operation of the image forming apparatus 100 . The nonvolatile memory control unit 134 controls the nonvolatile memory (not shown) in the image forming apparatus 100 .

[0026] The medium detection sensor control unit 135 reads the sensor states of the HOP sensor 119A, IN1 sensor 119B, IN2 sensor 119C, WR sensor 119D, and EXIT sensor 119E to obtain the paper presence / absence state.

[0027] The paper transport control unit 142 manages the ID drive motor 120 (see FIG. 1) so that each of the transport rollers 118A to 118V operates at the paper transport speed. Each of the transport rollers 118A to 118V rotates in conjunction with the ID drive motor 120.

[0028] The fixing control unit 143 uses the fixing drive motor 121 (see FIG. 1) to drive the fixing unit 114, and controls the temperature of a heat source (not shown) to achieve an appropriate toner melting temperature depending on the type of medium, the ambient temperature, and humidity. The fixing control unit 143 also adjusts the rotation speed of the fixing drive motor 121 to control the medium conveyance speed of the fixing unit 114.

[0029] The image formation control unit 136 controls the processing related to the formation of an image. For example, the image formation control unit 136 controls an image forming operation (also called a printing operation) that forms a toner image based on a print job as an image forming job. In addition, the image forming control unit 136 calculates the amount of toner to be discarded for each predetermined image forming unit (here, one page) according to the ratio of toner images to one sheet of paper, and if the total amount of discarded toner is greater than a predetermined discard threshold, causes the ID unit 104 to execute a developer discarding operation (also called a toner discarding operation) to discard toner at a predetermined timing.

[0030] When a predetermined condition is satisfied, the image formation control unit 136 executes the developer disposal operation not at a predetermined timing but during a period when the image forming operation is stopped. In the developer disposal operation, the ID unit 104 discards the toner used in the toner image.

[0031] Here, the predetermined condition is that the cumulative amount of waste is greater than the waste threshold at the start of the image formation operation and the internal temperature is predicted to reach or exceed the operation stop threshold before the image formation operation is completed, or that the internal temperature is predicted to reach or exceed the operation stop threshold during the image formation operation and the cumulative amount of waste is predicted to reach or exceed the waste threshold at the completion of the image formation operation.

[0032] As will be described later, the internal temperature control unit 144 calculates a temperature gradient, which is the change in internal temperature per unit time, from the amount of change in internal temperature over a predetermined period, and calculates a predicted internal temperature by multiplying the temperature gradient by the time remaining until the image formation operation is completed. If the predicted internal temperature is equal to or greater than the operation stop threshold, the internal temperature control unit 144 predicts that the internal temperature will reach or exceed the operation stop threshold before the image formation operation is completed.

[0033] Furthermore, the image formation control unit 136 calculates a predicted waste amount by multiplying the average value of the toner waste amount for a predetermined number of image formation units included in the image formation job by the number of remaining image formation units in the image formation job, and calculates a predicted cumulative waste amount by adding the predicted waste amount to the cumulative waste amount. If the predicted cumulative waste amount is greater than the waste threshold, the image formation control unit 136 predicts that the cumulative waste amount will be greater than the waste threshold when the image formation operation is completed.

[0034] The image forming control unit 136 includes an image output control unit 137, a toner waste control unit 138, a toner waste pattern generation control unit 139, a cumulative toner waste dot count control unit 140, and a cumulative toner waste dot count increase gradient calculation unit 141.

[0035] The image output control unit 137 controls the LED head 111, the ID unit 104, and the transfer roller 113 in response to a print instruction from a host computer, thereby controlling the transfer of an image onto a medium. The toner waste control unit 138, the toner waste pattern generation control unit 139, the cumulative toner waste dot count control unit 140, and the cumulative toner waste dot count increase gradient calculation unit 141 control the waste of degraded toner, as will be described later.

[0036] Next, the process of discarding deteriorated toner will be described. The image forming apparatus 100 applies a negative voltage to the supply roller 107 and the development roller 108 to move the toner supplied from the toner cartridge 112 to the photosensitive drum 105. Once the toner is charged, it deteriorates over time.

[0037] If the print duty is defined as the print rate relative to the entire paper, for example, in cases where there is a lot of high-duty printing with a high print rate relative to the entire paper, the toner that has been charged once is immediately used for printing, so there is a high possibility that the toner will be used before it deteriorates. On the other hand, if there is a lot of low-duty printing with a low printing rate relative to the entire paper, it takes time for the toner that has been charged to be used for printing, and there is a high possibility that it will deteriorate. The print duty can also be said to be the ratio of the developer image to one sheet of paper as a recording medium.

[0038] Here, the number of dots required for printing will be explained using the dot count, which is the actual number of dots divided by a predetermined value, because the value will be very large if calculated using the actual number of dots. The predetermined value here is "8192 (=2 13 ) but is not limited to this number.

[0039] For example, when printing on A4 paper with a print duty of 5%, the actual number of dots is 6,488,064, but the dot count is 792 = (6,488,064 ÷ 8,192). Therefore, when the print duty is 1%, the dot count is 158.4 (≒ 792 ÷ 5).

[0040] Here, the drum count is the average number of rotations of the photosensitive drum 105 when printing one predetermined medium (here, for example, A4). Furthermore, the slice value is assumed to be a print duty (%) per drum count. Then, the slice value serving as a threshold value for determining whether or not the toner on the photosensitive drum 105 has deteriorated to the extent that it needs to be discarded in one printing operation (image forming operation) is set as the "deteriorated toner discard slice value S." Further, the advance (increment) of the drum count of the photosensitive drum 105 in one printing operation is defined as "drum count advance O in printing (image formation)." Furthermore, the dot count as a threshold for determining whether or not the toner on the photosensitive drum 105 has deteriorated to the point where it needs to be discarded in one printing operation is defined as a "discard threshold dot count SL." The dot count printed on the photosensitive drum 105 in one printing operation is defined as "dot count D," and the dot count of degraded toner to be discarded in one printing operation is defined as "discard dot count WL." Here, the waste dot count WL corresponds to the amount of toner to be discarded.

[0041] In the above definitions, the "discard threshold dot count SL" and the "discard dot count WL" are calculated using the following equations (1) and (2). SL = 792 ÷ 5 × S × O (1) WL=SL-D (2)

[0042] A specific example will be used to explain this. The degraded toner discard slice value S is "1.5%", the dot count D used in printing A is "95.04", and the drum count advance O in printing A is "2". The discard threshold dot count SL is SL=792÷5×1.5×2=475.2. The discarded dot count WL is WL=475.2-95.04=380.16.

[0043] The waste dot count WL (=380.16) for printing A is added to the cumulative toner waste dot count TWL for each printed page. The cumulative toner waste dot count TWL corresponds to the cumulative waste amount. If the dot count D in print A is larger than the discard threshold dot count SL, the value of the discard dot count WL will be smaller. On the other hand, if the dot count D in print A is smaller than the discard threshold dot count SL, the value of the discard dot count WL will be larger.

[0044] The cumulative toner waste dot count TWL indicates the cumulative amount of degraded toner. Therefore, as the cumulative toner waste dot count TWL increases, the amount of degraded toner increases, and as the cumulative toner waste dot count TWL decreases, the amount of degraded toner decreases.

[0045] When the cumulative toner waste dot count TWL exceeds a predetermined threshold, it becomes necessary to discard the deteriorated toner. Here, as an example, the threshold is assumed to be "0." In other words, when the cumulative toner waste dot count TWL is "0" or less, it indicates that there is no accumulation of deteriorated toner. Note that the threshold is not fixed, but varies depending on the toner properties, the structure and operating time of the ID unit 104, etc., and is therefore determined appropriately through experiments, etc. The threshold here corresponds to the discard threshold.

[0046] When the cumulative toner waste dot count TWL becomes greater than "0", the toner waste control unit 138 discards the deteriorated toner accumulated in the ID unit 104 using a predetermined toner waste pattern. 3, the toner waste control unit 138 forms a toner image of a predetermined toner waste pattern on the photosensitive drum 105. The toner image of the toner waste pattern is scraped off by a cleaning blade 109 that contacts the photosensitive drum 105, and the scraped toner is collected in a waste toner collection container 110. Here, the toner waste pattern is an electrostatic latent image pattern with a print duty of 50%, in which black and white pixel values ​​of "1, 0, 1, 0, 1, 0, . . . " are repeated for 1364 lines in the main scanning direction of the photosensitive drum 105 in the sub-scanning direction.

[0047] As a result of the above, the amount of deteriorated toner corresponding to the deteriorated toner discard execution dot count WLa is discarded. For example, in the toner discard pattern shown in FIG. 3, the degraded toner discard execution dot count WLa=6,809,088 dots / 8192=831 dot count. Therefore, by discarding this degraded toner, the degraded toner discard execution dot count WLa, which indicates the amount of discarded degraded toner, is subtracted from the cumulative toner discard dot count TWL. Here, 831 dot counts are one unit of toner waste. Therefore, the toner waste control unit 138 causes the photosensitive drum 105 to form a toner image of the toner waste pattern by the number of units that will make the cumulative toner waste dot count TWL a value of "0" or less.

[0048] 2, the toner discard pattern generation control unit 139 generates discard image data indicating a toner discard pattern. The generated discard image data is provided to the toner discard control unit 138 and used to discard the deteriorated toner.

[0049] The cumulative toner waste dot count control unit 140 calculates the cumulative toner waste dot count TWL for each page printed.

[0050] The cumulative toner waste dot count increase gradient calculation unit 141 calculates the increase gradient of the cumulative toner waste dot count TWL during one print job corresponding to one printing operation. For example, for each page printed, the cumulative toner waste dot count increase gradient calculation unit 141 calculates the average value of the waste dot count WL for the past 10 pages from the current page as the increase gradient, as shown in Fig. 4. The increase gradient is a coefficient used to calculate a value for determining whether or not the toner waste operation can be brought forward when the internal temperature is at a high temperature stop, as described below. It should be noted that the past 10 pages here are merely an example for the purpose of explanation, and the present invention is not limited to such values.

[0051] The internal temperature control unit 144 controls the process of stopping printing in the image forming apparatus 100 according to the internal temperature of the image forming apparatus 100 . Here, the internal temperature control unit 144 causes the ID unit 104 to stop the image forming operation when the internal temperature reaches or exceeds a predetermined operation stop threshold value. The internal temperature control unit 144 includes a temperature detection control unit 145 and a temperature gradient calculation unit 146 .

[0052] The temperature detection control unit 145 uses the internal temperature sensor 117 to detect the internal temperature near the ID unit 104 at regular intervals (for example, every 10 seconds).

[0053] If the internal temperature is equal to or higher than a predetermined temperature (for example, 57°C) that is a print stop temperature, the temperature detection control unit 145 determines that the temperature inside the device is close to the toner melting temperature and there is a possibility that the toner may stick, and stops the printing operation of the image forming apparatus 100. For example, the temperature detection control unit 145 notifies the main control unit 132 and the image output control unit 137 of the internal temperature high stop state, and stops the printing operation. The print stop temperature is also called the operation stop threshold.

[0054] Furthermore, after the printing operation has stopped, if the internal temperature falls below a predetermined temperature (for example, 56°C) at which printing is to end, the temperature detection control unit 145 resumes the printing operation in the image forming apparatus 100. For example, the temperature detection control unit 145 notifies the main control unit 132 and the image output control unit 137 of the resumption of printing, and resumes the printing operation. The print stop end temperature is also referred to as the operation stop end threshold.

[0055] The temperature gradient calculation unit 146 calculates a temperature gradient that indicates the tendency of the amount of change in the internal temperature measured by the temperature detection control unit 145 . For example, the temperature gradient calculation unit 146 calculates an average value for each predetermined period (here, 50 seconds) as shown in FIG. Here, the temperature gradient calculation unit 146 calculates the average internal temperature from the present to 40 seconds ago, the average internal temperature from 10 seconds ago to 50 seconds ago, the average internal temperature from 20 seconds ago to 60 seconds ago, the average internal temperature from 30 seconds ago to 70 seconds ago, the average internal temperature from 40 seconds ago to 80 seconds ago, and the average internal temperature from 50 seconds ago to 90 seconds ago.

[0056] Then, the temperature gradient calculation unit 146 calculates the amount of temperature change over the most recent 100 seconds and the temperature change value per second using the following equations (3) and (4). Temperature change in the last 100 seconds = (average internal temperature from the current time to 40 seconds ago) - (average internal temperature from 50 seconds ago to 90 seconds ago) (3) Temperature change per second = (Temperature change in the last 100 seconds) ÷ 100 (4) The temperature change value per second is the temperature gradient.

[0057] In addition, to predict the future internal temperature, the temperature gradient calculation unit 146 multiplies the time required to print the unprinted pages of the print job obtained from the main control unit 132 by the temperature change value per second to calculate the expected internal temperature at the time printing of the print job is completed. If this temperature is equal to or higher than the print stop temperature, a high internal temperature stop state will occur before the print job is completed.

[0058] Some or all of the above-described command decode control unit 131, main control unit 132, initial control unit 133, nonvolatile memory control unit 134, medium detection sensor control unit 135, image formation control unit 136, paper transport control unit 142, fixing control unit 143, and internal temperature control unit 144 can be configured, for example, as shown in FIG. 6(A), by a memory 10 and a processor 11 such as a CPU (Central Processing Unit) that executes a program stored in memory 10. Such a program may be provided over a network or may be provided by being recorded on a recording medium. That is, such a program may be provided, for example, as a computer program product.

[0059] In addition, some or all of the command decode control unit 131, main control unit 132, initial control unit 133, non-volatile memory control unit 134, medium detection sensor control unit 135, image formation control unit 136, paper transport control unit 142, fixing control unit 143 and internal temperature control unit 144 can also be configured with a processing circuit 12 such as a single circuit, a composite circuit, a processor operated by a program, a parallel processor operated by a program, an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array), for example, as shown in Figure 6 (B). As described above, the command decode control unit 131, main control unit 132, initial control unit 133, non-volatile memory control unit 134, medium detection sensor control unit 135, image formation control unit 136, paper transport control unit 142, fixing control unit 143, and internal temperature control unit 144 can be realized by a processing circuit network.

[0060] 7 to 9 are flowcharts showing the operation of image forming apparatus 100 according to the embodiment. In Figures 7 to 9, it is assumed that upon receiving a print instruction from a higher-level host (not shown), the main control unit 132 instructs the paper transport control unit 142, the fixing control unit 143, and the image formation control unit 136 to start printing, and printing has begun.

[0061] First, the image forming control unit 136 determines whether printing of all print pages of the print job for which printing has been instructed has been completed (S10). If printing of all print pages has been completed (Yes in S10), the operation ends. If printing of all print pages has not been completed, in other words, if there are print pages remaining to be printed (No in S10), the process proceeds to step S11.

[0062] In step S11, temperature detection control unit 145 detects the internal temperature of image forming apparatus 100, and temperature gradient calculation unit 146 calculates the temperature gradient, which is the temperature change value per second, from the amount of change in the internal temperature over a predetermined period. Here, temperature gradient calculation unit 146 calculates the temperature change value per second as the temperature gradient from the amount of temperature change over the most recent 100 seconds.

[0063] Next, the cumulative toner waste dot count control unit 140 calculates the cumulative toner waste dot count TWL for each page printed, and the cumulative toner waste dot count increase gradient calculation unit 141 calculates the average value of the waste dot count WL for a predetermined number of pages as the increase gradient of the cumulative toner waste dot count TWL (S12). Here, the cumulative toner waste dot count increase gradient calculation unit 141 calculates the average value of the waste dot count WL for the past 10 pages from the present as the increase gradient of the cumulative toner waste dot count TWL. However, if the predetermined number of pages have not yet been printed, the cumulative toner waste dot count increase gradient calculation unit 141 does not calculate the increase gradient.

[0064] Next, the image output control unit 137 determines whether the print is the first page of the print job (S13). If the print is the first page (Yes in S13), the process proceeds to step S20 in Fig. 8, and if the print is not the first page (No in S13), the process proceeds to step S14.

[0065] Next, the temperature detection control unit 145 determines whether the detected internal temperature is equal to or higher than a predetermined print stop temperature (here, 57° C.) (S14). If the internal temperature is equal to or higher than the print stop temperature (Yes in S14), the process proceeds to step S30 in FIG. 9, and if the internal temperature is lower than the print stop temperature (No in S14), the process proceeds to step S15.

[0066] In step S15, the paper conveyance control unit 142, the fixing control unit 143, and the image formation control unit 136 can continue printing, so they execute printing for one page. For example, the image output control unit 137 executes output of an image for one page. Then, the image output control unit 137 determines whether or not the output of one page of image has been completed (S16). If the output of one page of image has been completed, the process proceeds to step S17.

[0067] In step S17, the toner waste control unit 138 calculates the dot count D and the drum count advance O for the one page printed in step S15.

[0068] Next, the cumulative toner waste dot count control unit 140 updates the waste dot count WL and the cumulative toner waste dot count TWL using the dot count D calculated in step S17 and the drum count advance O (S18).Then, the process returns to step S10, and printing of the next page is considered.

[0069] In step S20 of Fig. 8, the toner waste control unit 138 determines whether the cumulative toner waste dot count TWL is greater than a predetermined threshold value (here, "0"). If the cumulative toner waste dot count TWL is greater than the threshold value, it is determined that a toner waste operation is necessary, and the process proceeds to step S21. If the cumulative toner waste dot count TWL is equal to or less than the threshold value (No in S20), it is determined that a toner waste operation is not necessary, and the process proceeds to step S14 of Fig. 7.

[0070] In step S21, the temperature detection control unit 145 determines whether or not printing is to be stopped due to a high temperature while printing of a print job is being executed. For example, the temperature detection control unit 145 calculates a predicted internal temperature, which is a predicted value of the internal temperature at the time when printing of the print job is completed, by multiplying the time required to print the number of unprinted pages in the print job by the temperature gradient calculated in step S11. Then, if the predicted internal temperature is equal to or higher than the print stop temperature, the temperature detection control unit 145 determines that printing will be stopped due to high temperature while printing of the print job is being executed.

[0071] If printing is stopped due to high temperature while the print job is being printed (Yes in S21), the process proceeds to step S14 in Fig. 7 because the degraded toner can be discarded when printing is stopped due to high temperature. This causes the first page to be printed. On the other hand, if printing is not stopped due to high temperature while printing the print job is being executed (No in S21), it is the first page of the print job, in other words, it is the predetermined timing, so it is determined that it is necessary to discard the deteriorated toner, and processing proceeds to step S22.

[0072] In step S22, the toner discarding pattern generation control unit 139 generates one or more units of the toner discarding pattern as shown in FIG. 4 so that the cumulative toner discarding dot count TWL becomes "0" or less.

[0073] The toner disposal control unit 138 uses the toner disposal pattern generated in step S22 to discard the deteriorated toner (S23).

[0074] Next, the cumulative toner waste dot count control unit 140 updates the cumulative toner waste dot count TWL using the deteriorated toner waste execution dot count WLa (S24). As a result, the cumulative toner waste dot count TWL becomes "0" or less, and the process proceeds to step S14 in FIG. 7. This causes the first page to be printed.

[0075] In step S30 of FIG. 9, the image output control unit 137 stops the printing operation due to high temperature stop.

[0076] Next, the toner waste control unit 138 determines whether the cumulative toner waste dot count TWL is greater than the predetermined threshold value of "0" (S31). If the cumulative toner waste dot count TWL is greater than the threshold value (Yes in S31), the process proceeds to step S33. If the cumulative toner waste dot count TWL is equal to or less than the threshold value (No in S31), the process proceeds to step S32.

[0077] In step S32, the toner waste control unit 138 calculates the predicted cumulative toner waste dot count ETWL, which is the cumulative toner waste dot count at the end of the current print job, using the following equation (5), and determines whether the predicted cumulative toner waste dot count ETWL is greater than the predetermined threshold value of "0".

[0078] ETWL = TWL + increase gradient × (number of remaining pages in the print job) (5)

[0079] If the predicted cumulative toner waste dot count ETWL is greater than the threshold value (Yes in S32), the process proceeds to step S33 to discard the deteriorated toner in advance, and if the predicted cumulative toner waste dot count ETWL is equal to or less than the predetermined threshold value (No in S32), the process proceeds to step S36 since there is no need to discard the deteriorated toner.

[0080] In step S33, the toner waste pattern generation control unit 139 generates one or more units of a toner waste pattern such as that shown in FIG. 3 so that the cumulative toner waste dot count TWL or the predicted cumulative toner waste dot count ETWL is equal to or less than "0". 3 is generated for one or more units so that the predicted cumulative toner waste dot count ETWL is equal to or less than 0 when the predicted cumulative toner waste dot count ETWL is equal to or greater than the threshold value in step S32. However, the embodiment is not limited to this example. For example, in this case, a toner waste pattern for a predetermined number of units may be generated.

[0081] The toner disposal control unit 138 uses the toner disposal pattern generated in step S33 to discard the deteriorated toner (S34).

[0082] Next, the cumulative toner waste dot count control unit 140 updates the cumulative toner waste dot count TWL using the deteriorated toner waste execution dot count WLa (S35). As a result, the cumulative toner waste dot count TWL becomes "0" or less, and the process proceeds to step S36.

[0083] In step S36, the temperature detection control unit 145 detects the internal temperature and determines whether the detected internal temperature is below a predetermined print stop end temperature (here, 56° C.). If the internal temperature is below the print stop end temperature (Yes in S36), the process proceeds to step S37.

[0084] In step S37, the high internal temperature stop state is released, and the image output control unit 137 performs print settings again based on the print job. Then, the process proceeds to step S15 in FIG.

[0085] Next, the relationship between the toner disposal operation and the high temperature shutdown due to the internal temperature of the device will be described. For example, as shown in Fig. 10, conventionally, in an image forming apparatus, after printing of a print job ends at time t01 and before printing of another print job starts, if the cumulative toner waste dot count exceeds the cumulative toner waste dot count threshold, degraded toner is discarded. In the example shown in Fig. 10, degraded toner is discarded between time t02 and time t03.

[0086] 11, conventionally, when the internal temperature of the device reaches or exceeds a predetermined print stop temperature (here, 57°C), the printing operation is stopped, and when the internal temperature falls below a predetermined print stop end temperature (here, 55°C), the printing operation is started. For this reason, in the example shown in FIG. 11, the printing operation is stopped between time t11 and time t12.

[0087] If the discarding of degraded toner as shown in FIG. 10 and the stopping of the device as shown in FIG. 11 are carried out separately, the total printing throughput will decrease.

[0088] In contrast, in this embodiment, for example, as shown in Figure 12, even if the cumulative toner waste dot count becomes greater than the threshold value at the end of a print job, Job1, if it is predicted that printing operations will be stopped due to high temperatures during printing of the next print job, Job2, to prevent a decrease in printing throughput by performing toner waste operation OP2 during the period when printing operations are stopped due to high temperatures, instead of toner waste operation OP1 that should be performed before printing the first page of Job2.

[0089] Furthermore, in this embodiment, for example, as shown in FIG. 13, if the predicted cumulative toner waste dot count becomes greater than a threshold value at the end of a print job, Job1, toner waste operation OP3, which should be performed before printing the first page of the next print job, Job2, is performed as toner waste operation OP4 during the period when printing operations are stopped due to high temperatures, thereby preventing a decrease in printing throughput.

[0090] As described above, in this embodiment, the execution of toner disposal is advanced or delayed to coincide with the timing of the printing operation being stopped due to the internal temperature becoming too high, thereby overlapping the stopping of the printing operation with the toner disposal operation, thereby preventing a decrease in printing throughput compared to when these are performed separately. The charged toner remains damaged unless it is used for printing. Therefore, by disposing of such damaged toner ahead of schedule, the amount of toner remaining for a long time is reduced, leading to improved print quality.

[0091] In this embodiment, the deteriorated toner discard slice value S is set to "1.5%", but this embodiment is not limited to this value. In this embodiment, the degraded toner discard execution dot count WLa is set to "831 dot counts," but this embodiment is not limited to this value.

[0092] In this embodiment, the ID unit 104 includes the waste toner collection container 110. However, this embodiment is not limited to this example. For example, the waste toner collection container 110 may be included inside the toner cartridge 112. In this case, when the waste toner collection container 110 becomes full, the toner cartridge 112 needs to be replaced.

[0093] In this embodiment, an electrostatic latent image is written onto the photosensitive drum 105 by the LED head 111, but this embodiment is not limited to this example. For example, instead of the LED head 111, a print head of another type, such as a laser head, may be used.

[0094] Although this embodiment has been described using a print head (9984 dots) that prints on A4 size paper, this embodiment is not limited to this example. In this embodiment, an example in which one ID unit 104 is provided is shown, but a plurality of ID units, such as three or four ID units, may be provided. [Explanation of symbols]

[0095] 100 Image forming device, 101 Media storage tray, 102 Pickup roller, 103 Tray hopping roller, 104 ID unit, 105 Photosensitive drum, 106 Charging roller, 107 Supply roller, 108 Developing roller, 109 Cleaning blade, 110 Waste toner collection container, 111 LED head, 112 Toner cartridge, 113 Transfer roller, 114 Fuser, 116 Ambient temperature and humidity sensor, 117 Internal temperature sensor, 130 I / F unit, 131 Command decode control unit, 132 Main control unit, 133 Initial control unit, 134 Non-volatile memory control unit, 135 Media detection sensor control unit, 136 Image forming control unit, 142 Paper transport control unit, 143 Fuser control unit, 144 Internal temperature control unit.

Claims

1. an image forming unit that forms a developer image using a developer; an internal temperature measuring unit that measures the temperature of a predetermined location as an internal temperature; an image formation control unit that controls an image forming operation for forming the developer image based on an image formation job, calculates a discard amount of the developer to be discarded in accordance with a ratio of the developer image to a recording medium for each predetermined image forming unit, and when a cumulative discard amount obtained by accumulating the discard amounts becomes greater than a predetermined discard threshold, causes the image forming unit to execute a developer discarding operation for discarding the developer at a predetermined timing; an internal temperature control unit that causes the image forming unit to stop the image forming operation when the internal temperature becomes equal to or higher than a predetermined operation stop threshold value; the image forming control unit executes the developer disposal operation during the period when the stop is being performed, rather than at the predetermined timing, when a predetermined condition is satisfied; In the developer discarding operation, the image forming unit discards the developer used for the developer image. An image forming apparatus comprising:

2. The predetermined condition is that the accumulated discard amount is greater than the discard threshold value at the start of the image forming operation, and the internal temperature is predicted to become equal to or greater than the operation stop threshold value before the image forming operation is completed, or that the internal temperature is predicted to become equal to or greater than the operation stop threshold value during the image forming operation, and the accumulated discard amount is predicted to become greater than the discard threshold value at the completion of the image forming operation.

2. The image forming apparatus according to claim 1, wherein:

3. The internal temperature control unit calculates a temperature gradient, which is a change value of the internal temperature per unit time, from an amount of change in the internal temperature over a predetermined period, calculates a predicted internal temperature by multiplying the temperature gradient by the remaining time until the image forming operation is completed, and when the predicted internal temperature is equal to or greater than the operation stop threshold, predicts that the internal temperature will become equal to or greater than the operation stop threshold before the image forming operation is completed.

3. The image forming apparatus according to claim 2, wherein:

4. The image formation control unit calculates a predicted discard amount by multiplying an average value of the discard amount for a predetermined number of image formation units included in the image formation job by the number of remaining image formation units of the image formation job, calculates a predicted accumulated discard amount by adding the predicted discard amount to the accumulated discard amount, and, if the predicted accumulated discard amount is greater than the discard threshold, predicts that the accumulated discard amount will be greater than the discard threshold upon completion of the image formation operation.

4. The image forming apparatus according to claim 2, wherein:

Images