JP7735157B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus.

For users of image forming devices, the shorter the first printout time (FPOT), which is the time from issuing a print command to when the paper with the image formed on it is ejected from the device, the better. FPOT is determined by the time it takes for the image data to be prepared by the image forming device's controller (image data preparation process), the preparation operation for the image forming device's engine control unit to start image formation (print preparation operation), and the printing operation to form the image on the paper.

To shorten this FPOT, one method is to start image formation preparation operations at the same time as starting image data preparation processing, and perform image data preparation processing and print preparation operations in parallel (hereinafter referred to as parallel preparation operations).

Patent Document 1 proposes a method in which excess time is defined as the difference between the time elapsed from the start of image formation preparatory operations to the start of image formation and a predetermined time, and whether or not to perform preparatory parallel operations is selected based on the value of the accumulated excess time. This proposed method can prevent unnecessary rotation of components such as the fixing unit, which would shorten their lifespan, when there are many print jobs in which the time required for image data preparation processing is longer than the time required for image formation preparatory operations.

JP 2010-228334 A

When the image forming device is operating in a printable state, in addition to the toner image formed based on image data, a small amount of toner (fog toner) adheres to the non-image forming areas on the photosensitive drum. Any toner that adheres to the photosensitive drum but is not transferred to paper is scraped off by a cleaning blade installed inside the cartridge and collected as waste toner in a waste toner container.

The amount of waste toner generated here varies depending on the content of the image data, the state of the toner image based on that image, and the amount of fog toner that occurs depending on the rotation time of the image forming device. Therefore, if there is a large amount of waste toner generated compared to the toner transferred to paper, the waste toner container will overflow before the cartridge reaches the end of its life.

That is, in process cartridge-type image forming devices, a process cartridge is known to have a waste toner container in addition to a photosensitive drum and a developing unit. In process cartridges with such a configuration, it may not be possible to clear the collected waste toner from the waste toner container due to device configuration or cost constraints. In this case, if the waste toner container becomes full, the waste toner container will overflow, making the entire process cartridge unusable before the process cartridge reaches the end of its life due to deterioration of the cartridge components, etc.

In particular, if preparatory parallel operation is performed to shorten FPOT and excess rotation time increases, more waste toner is generated, increasing the risk of the waste toner container overflowing. On the other hand, if the decision to perform preparatory parallel operation to prevent waste toner overflow is based on the accumulated excess time, as described in Patent Document 1, preparatory parallel operation will be restricted regardless of the status of waste toner collection in the waste toner container, limiting opportunities to shorten FPOT.

The present invention was made in consideration of the above-mentioned problems, and aims to provide an image forming device that reduces the first printout time while preventing waste toner overflow.

The present invention employs the following configuration:
a process cartridge including: an image carrier configured to form an electrostatic latent image on its surface in accordance with image data; a developing roller that supplies toner to the image carrier and develops the electrostatic latent image to form a toner image on the image carrier, the developing roller being in contact with the image carrier; recovery means that recovers residual toner, which is the toner that remains without being transferred from the image carrier; and storage means that stores the recovered residual toner;
a control means for causing the process cartridge to start preparation for printing and for causing the process cartridge that has completed preparation for printing to start a printing operation;
an image processing means for performing a preparatory process for the image data, which instructs the control means to start the print preparation, and after the preparatory process is completed, instructs the control means to start the print operation;
and
the control means causes the process cartridge to start the printing operation when the print preparation of the process cartridge is completed and an instruction to start the printing operation is output from the image processing means,
a collected amount detecting means for detecting an accumulated collected amount of the residual toner stored in the storing means;
The image forming apparatus is characterized in that, when the control means receives an instruction to start the printing preparation from the image processing means, it compares the accumulated recovered amount of the remaining toner detected by the recovered amount detection means with a predetermined threshold, and if the accumulated recovered amount is equal to or greater than the threshold, it delays the timing of starting the printing preparation compared to when the accumulated recovered amount is less than the threshold.

The present invention also employs the following configuration:
An image forming apparatus that receives an external instruction to form an image on a recording material and discharges the image,
a process cartridge including: an image carrier on whose surface an electrostatic latent image is formed in accordance with image data; a developing unit that supplies toner stored inside to the image carrier by a developing roller to develop the electrostatic latent image; a recovery unit that recovers residual toner, which is the toner that remains without being transferred from the image carrier to the recording material; and a storage unit that stores the recovered residual toner;
When the printout time is defined as the time from receiving the external instruction to discharging the recording material on which the image is formed, the image forming apparatus is characterized in that, even when the same image is printed, the printout time when the amount of remaining toner contained in the storage means is a first amount is longer than the printout time when the amount of remaining toner contained in the storage means is a second amount that is less than the first amount.

This invention provides an image forming device that prevents waste toner overflow while shortening the first printout time.

1 is a schematic diagram of an image forming apparatus according to the present invention; 1 is a block diagram showing a system configuration of an image forming apparatus according to the present invention; 4 is a timing chart showing a printing operation according to the present invention. 4 is a timing chart showing a printing operation according to the present invention. 4 is a timing chart showing a printing operation according to the present invention. 6 is a flowchart for determining the start of a print preparation operation in the first embodiment. 10 is a flowchart for determining the start of a print preparation operation in the second embodiment. 10 is a flowchart for determining the start of a print preparation operation in the third embodiment.

The following describes in detail the embodiments of the present invention, by way of example, with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, and relative arrangements of the components described in these embodiments may be modified as appropriate depending on the configuration and various conditions of the device to which the invention is applied. In other words, it is not intended that the scope of the present invention be limited to the following embodiments.

Example 1
[Overall Configuration of Image Forming Apparatus]
1 is a cross-sectional view of an image forming apparatus according to the present embodiment, in which a laser beam printer 100 (hereinafter referred to as printer 100) is used as the image forming apparatus.

In FIG. 1, the photosensitive drum 122 (image carrier) is made of an organic photosensitive material or an amorphous silicon photosensitive material, and is rotated clockwise at a predetermined peripheral speed (process speed). The peripheral surface of this photosensitive drum 122 is uniformly charged to a predetermined polarity and potential by a charging roller 123. A laser beam output from the scanner 108 is then irradiated onto this charged surface, forming an electrostatic latent image on the photosensitive drum 122. The scanner 108 modulates (ON/OFF conversion) the laser beam in accordance with the time-series digital pixel signal under the control of the exposure control unit 208. The timing for starting scanning exposure in the sub-scanning direction is notified to the image signal generating device from the printer 100 by a sub-scanning direction synchronization signal.

Toner is stored inside the developing unit 125 (developing means). A voltage is applied to the developing roller 121 and the supply roller 124, and the developing roller 121 receives a supply of toner from the supply roller 124 as they are rotated and driven at a uniform potential. In this way, an electrostatic latent image formed on the surface of the photosensitive drum 122 corresponding to the desired image is developed by the developing roller 121, which is in contact with the photosensitive drum 122 while a voltage is applied. Here, it is assumed that the photosensitive drum 122 and developing roller 121 of the present invention are always in contact with each other.

The printer 100 is provided with a paper feed tray 140 (paper feed port) on which paper P (recording material) is placed. Paper feed rollers 101 feed paper P from the paper feed tray 140. A registration sensor 105 detects when the paper P reaches registration rollers 104. The paper P is then fed toward the photosensitive drum 122 by the registration rollers 104, and a mirror image of the toner image on the photosensitive drum 122 is formed on the paper P.

The transfer roller 106 transfers the toner image from the photosensitive drum 122 to the paper P by supplying a charge of the opposite polarity to the toner from the back surface (non-image forming surface) of the paper P. Residual toner that has not been transferred to the paper P and remains on the photosensitive drum 122 is scraped off by a cleaning blade 126 (collection means) and collected in a waste toner container 127 (storage means).

The paper P with the transferred toner image is separated from the photosensitive drum 122 and sent to the fixing device 130, where the toner image is fixed. The fixing device 130 is composed of a thermistor 131, a heater 132, a fixing film 133, and a pressure roller 134. The fixing and ejection sensor 109 detects that the paper P with the thermally fixed image has passed through the fixing device 130 normally, and the paper is then conveyed by the paper ejection rollers 111 and ejected onto the paper ejection tray 112.

In the printer 100 of this embodiment, the photosensitive drum 122, charging roller 123, developer 125, and waste toner container 127 are integrated into a process cartridge 150. The process cartridge 150 is configured to be detachable from the printer body.

[System Configuration of Image Forming Apparatus]
Next, the system configuration of the printer 100 will be described. Fig. 2 is a block diagram for explaining the system configuration of the printer 100. In Fig. 2, the printer 100 includes a controller unit 201 (image processing means) and an engine control unit 202 (control means). The controller unit 201 is capable of mutual communication with a host computer 200, which is an external device. The controller unit 201 is also capable of mutual communication with the engine control unit 202 via a video interface unit 203.

The host computer 200, which is an external device, sends print conditions, image data of the print image, and print commands to the controller unit 201 of the printer 100. The controller unit 201 converts the image data received from the host computer 200 into the exposure data required for the printer 100, and creates print reservation information for each sheet of paper based on the received print conditions. Examples of print reservation information include the paper feed slot (such as paper feed tray 140) indicating the source of the paper P, the size of the paper P, and the print mode.

The controller unit 201 sends a print reservation instruction for the page to the engine control unit 202 via the video interface unit 203, and once the conversion from image data to exposure data is complete, it sends a print start instruction to the engine control unit 202. When the engine control unit 202 receives the print start instruction from the controller unit 201, it starts the print operation. The exposure data converted by the controller unit 201 is sent as a pixel signal to the exposure control unit 208 via the video interface unit 203, and is also sent to the pixel signal counting unit 224. The pixel signal counting unit 224 counts pixel signals during image formation and sends the total count number for each page to the engine control unit 202 as a pixel signal value.

The drive control unit 209 drives and rotates each roller of the printer 100 using the main motor 204. The main motor 204 drives and rotates the paper feed roller 101, registration roller 104, photosensitive drum 122, transfer roller 106, pressure roller 134, and paper discharge roller 111. The main motor 204 and paper feed roller 101 are connected via a paper feed clutch 214, and when paper P is fed from the paper feed tray 140, the paper feed clutch 214 is engaged for a predetermined time, causing the paper feed roller 101 to be driven and rotated.

In response to instructions from the engine control unit 202, the exposure control unit 208 rotates the scanner motor (not shown) provided in the scanner 108 and corrects the exposure amount, and controls the irradiation of laser light onto the photosensitive drum 122 based on exposure data received from the controller unit 201.

The high-voltage control unit 210 controls the power supply that applies DC voltages, such as charge roller voltage 220, development roller voltage 221, supply roller voltage 222, and transfer roller voltage 223, to the charge roller 123, development roller 121, supply roller 124, and transfer roller 106, which are components within the printer 100.

A fixing control unit 211 detects the surface temperature of the heater 132 using the thermistor 131 and controls the power supply to the heater 132. A sensor input unit 212 acquires detection information from the registration sensor 105 and the fixing paper discharge sensor 109 and outputs the information to the engine control unit 202. A cartridge memory communication unit 215 reads and writes information by communicating with a non-volatile cartridge memory (not shown) mounted on the cartridge via a two-wire serial method.

The controller unit 201, engine control unit 202, video interface unit 203, pixel signal counting unit 224, exposure control unit 208, drive control unit 209, high voltage control unit 210, fixing control unit 211, and sensor input unit 212 may be realized by an information processing device equipped with computing resources such as a processor and memory, or a processing circuit such as an FPGA or ASIC. Each of the above components may be realized by a separate information processing device or processing circuit, or a single information processing device or processing circuit may realize multiple components.

[Print preparation operation and image formation operation]
A description will be given of the print preparation operation (preparatory operation for image forming operation) and print operation (image forming operation) of the printer 100 configured as described above. Figures 3A to 3C are timing charts showing the differences in each print operation depending on whether or not the preparatory parallel operation is performed.

(When preparatory parallel operation is not performed)
3A shows a case where the image data preparation process and the print preparation process are not performed in parallel. At t301, the host computer 200, which is an external device, starts image processing, and when the image processing is completed (t302), the host computer 200 notifies the controller unit 201 of a print instruction together with the image data.

When the controller unit 201 receives a print instruction, it starts the process of converting image data into bitmap data, and when the image conversion process (image data preparation process) is completed (t303), it issues a print instruction to the engine control unit 202. The time required for this image conversion process is defined as T0a.

When an instruction to start a printing operation is received in preparation for printing, the engine control unit 202 drives the components of the process cartridge 150 so that the image forming apparatus can actually print. The engine control unit 202 starts the print preparation operation by driving the main motor 204 of the image forming apparatus to rotate the photosensitive drum 122 and by starting the supply of toner to the photosensitive drum 122 by the developing roller 121. The engine control unit 202 drives the main motor 204, causes the charging roller 123 to uniformly charge the surface of the photosensitive drum 122, and causes the supply roller 124 to supply toner to the developing roller 121. The fixing control unit 211 also starts powering up the fixing heater 132.

When an instruction to start a printing operation is received, the image forming apparatus is ready to actually print, and the print preparation operation is completed. In this embodiment, the print preparation operation is completed when a predetermined time (T1) has elapsed since the start of fixing startup (t304). The engine control unit 202 drives the paper feed clutch 214 and feeds paper P from the paper feed tray 140. At a predetermined timing after the leading edge of paper P passes the registration sensor 105, the engine control unit 202 outputs a sub-scanning direction synchronization signal, which serves as the reference timing for outputting digital pixel signals, to the controller unit 201 (t305).

As described above, the photosensitive drum 122 and the developing roller 121 are in constant contact with each other. With this configuration, when the photosensitive drum 122 and the developing roller 121 are rotating, fog toner always adheres to the photosensitive drum 122. Here, fog toner refers to toner that adheres to areas of the photosensitive drum 122 that are not areas where an image is originally intended to be formed. Therefore, in this embodiment, fog toner is generated even during the print preparation operation while the photosensitive drum 122 is rotating. Since the fog toner thus generated is ultimately collected in the waste toner container 127, if the amount of toner already collected in the waste toner container 127 is large, there is a risk that the container will overflow due to the fog toner during the print preparation operation, and therefore measures are required.

Based on the digital pixel signals received from the controller unit 201, the engine control unit 202 exposes the photosensitive drum 122 with the scanner 108 to form an electrostatic latent image, and causes the developing roller 121 to deposit toner onto the photosensitive drum 122. The engine control unit 202 then applies a DC voltage of the opposite polarity to the toner image formed on the photosensitive drum 122 to the transfer roller 106, transferring the toner image on the photosensitive drum 122 to the paper P and transporting it.

After the image data has been transmitted (t306), the paper P is peeled off the photosensitive drum 122 and transported to the fixing device 130. The image on the paper P is then fixed in the fixing nip formed by the fixing film 133 and pressure roller 134, and the paper is then ejected, with the image side facing down, via the paper ejection rollers 111 onto the paper ejection tray 112 at the top of the main body.

The engine control unit 202 stops the print transport and driving of the main motor 204 when the paper passes the paper discharge rollers 111 (t307). The driving time of the main motor 204 at this time is the period from t303 to t307 (T2a), and the first printout time (FPOT, first time), which is the time from when a print command is issued until the paper with an image formed on it is discharged outside the device, is the period from t302 to t307 (T3a).

(When performing preparatory parallel operations)
3B is a timing chart showing the printing operation when the preparatory parallel operation is performed. Hereinafter, the same processes as those in FIG. 3A will not be described. At t311, the host computer 200, which is an external device, starts image processing, and at the point in time when the image processing is completed (t312), the host computer 200 notifies the controller unit 201 of a print instruction together with the image data.

When the controller unit 201 receives a print instruction, it notifies the engine control unit 202 of a pre-command indicating the start of print preparation, and starts the process of converting the image data into bitmap data. The controller unit 201 issues a print instruction to the engine control unit 202 when the image conversion process is completed (t313). The time required for the image conversion process at this time is T0b, and in this case T0b = T0a.

When the engine control unit 202 receives the pre-command, it begins print preparation as described in Figure 3A, and when the predetermined time T1 has elapsed, it completes print preparation (t314). Because the engine control unit 202 has already received the print instruction at t313, which is earlier than t314, the engine control unit 202 drives the paper feed clutch 214 at t314 and feeds paper P from the paper feed tray 140.

The rest of the process is the same as in Figure 3A. After the controller unit 201 sends image data (t315 to t316), the engine control unit 202 stops print transport and driving of the main motor 204 after the paper is ejected (t317). The driving time of the main motor 204 at this time is the period from t312 to t317 (T2b), and T2b is equal to T2a. The FPOT time is the period from t312 to t317 (T3b), and T3b is equal to T2b.

Comparing T3a, the FPOT in Figure 3A, with T3b, the FPOT in Figure 3B, we see that T3a is longer than T2a. Therefore, T3b is shorter than T3a. Therefore, it can be seen that the FPOT in Figure 3B is shorter than in Figure 3A.

3C is a timing chart showing the printing operation when the preparatory parallel operation is performed, similar to FIG. 3B, but differs from FIG. 3B in that the time taken for the controller unit 201 to perform the image development process is longer. At t321, the host computer 200, which is an external device, starts image processing, and at the point in time when the image processing is completed (t322), the host computer 200 notifies the controller unit 201 of a print instruction together with the image data.

When the controller unit 201 receives a print instruction, it notifies the engine control unit 202 of a pre-command indicating the start of print preparation, and starts the process of converting image data into bitmap data. When the engine control unit 202 receives the pre-command, it starts print preparation as described in Figure 3A, and after a predetermined time T1 has elapsed, it considers print preparation to be complete (t323). At this point, the controller unit 201 is in the middle of image conversion processing and has not yet notified the engine control unit 202 of a print instruction, so the engine control unit 202 waits for notification of a print instruction without performing a paper feed operation (t323).

When the image development process is completed (t324), the controller unit 201 issues a print instruction to the engine control unit 202. The time required for the image development process at this time is T0c, which in this case is longer than T0b and shorter than the time T0a + T1. When the print instruction is received at t324, the engine control unit 202 drives the paper feed clutch 214 and feeds paper P from the paper feed tray 140.

The rest of the process is the same as in Figure 3A. After the controller unit 201 sends image data (t325-t326), the engine control unit 202 stops print transport and driving of the main motor 204 after the paper is ejected (t327). The driving time of the main motor 204 at this time is the period from t322 to t327 (T2c), which is longer than T2b and T2a. On the other hand, the FPOT time is the period from t322 to t327 (T3c), which is equal to T2c. Also, the time T0c from the start of print preparation (t322) to paper feeding (t324) is shorter than the time (T0a + T1) in Figure 3A, so the FPOT is shorter in Figure 3C than in Figure 3A. On the other hand, the drive time of the main motor 204 increases by the amount of excess time compared to the cases of Figures 3A and 3B, and this increased time is the "wait" time (T0c-T1) from t323 to t324.

[Detection of collected waste toner amount]
Next, the detection of the amount of collected waste toner used in this embodiment will be described. The amount of collected waste toner is calculated by predicting the amount of waste toner due to fog toner generated during periods when image formation is not occurring (non-printing periods) and the amount of waste toner due to toner images and fog toner generated based on image data during periods when image formation is occurring (printing periods), and adding these amounts of waste toner together. This calculation process can be performed by an information processing device or processing circuit provided in the image forming apparatus 100, such as the engine control unit 202. In this case, the engine control unit 202 functions as a collected amount detection unit that detects the cumulative amount of collected residual toner.

The printing period in Figure 3A is the period from t305 to t306. The non-printing period is the period when the main motor is driving and no printing is occurring, and is the period from t303 to t307 excluding t305 to t306. Similarly, the printing period in Figure 3B is the period from t315 to t316, and the non-printing period is the period when the main motor is driving (t312 to t317) and no printing is occurring. The printing period in Figure 3C is the period from t325 to t326, and the non-printing period is the period when the main motor is driving (t322 to t327) and no printing is occurring.

The amount of waste toner is predicted based on the pixel signal values sent from the pixel signal counting unit 224 to the engine control unit 202. During the printing period, of the amount of waste toner generated per page, the amount of waste toner (Wdt) due to the toner image based on image data is calculated using formula (1), and the amount of waste toner (Wbg) due to fog toner is calculated using formula (2).

Wdt=P×A…(1)
Here, P and A are as follows:
P: The number of pixels sent from the pixel signal counting unit 224 to the engine control unit 202.
A: Amount of waste toner formed on the drum surface during the printing period per pixel. This is a predetermined value, expressed in units of [%/pixel].

Wbg=(T-P)×B…(2)
where T and B are as follows:
T: total number of pixels during image formation, determined by the drum rotation distance [mm] during the printing period and the number of pixels per predetermined drum rotation distance [pixels/mm].
B: Amount of waste toner during the printing period per pixel where no toner is formed on the drum surface. This is a predetermined value, expressed in units of [%/pixel].

During non-printing periods, the amount of waste toner (Wrt) generated according to the rotation distance of the photosensitive drum is calculated using formula (3). Here, the unit of waste toner amount is %, with 100% being when the waste toner container is full. During printing periods, toner on the photosensitive drum is primarily transferred to paper, but during non-printing periods, it remains on the photosensitive drum without being transferred to paper. Therefore, the proportion of toner formed on the photosensitive drum that becomes waste toner is greater during non-printing periods than during printing periods.

Wrt=L×C…(3)
Here, L and C are as follows:
L: drum rotation distance [mm].
C: Amount of waste toner during a non-printing period per distance on the drum surface where no toner is formed. This is a predetermined value, and the unit is [%/mm].

From these waste toner amounts, the amount of waste toner collected in the waste toner container per job (Wjob) is calculated using formula (4) each time a print job is executed, and the total amount of waste toner collected in the waste toner container (W) is calculated using formula (5). In other words, the amount of waste toner generated increases as the rotation distance (rotation time) per job increases. The value of this total amount of waste toner collected (W) is also recorded in non-volatile cartridge memory (not shown).

Wjob=Wdt+Wbg+Wrt...(4)

W=W+Wjob…(5)
However, W<=100[%]

In this embodiment, the method for calculating the amount of collected waste toner is not limited to the above example, and any method for determining the amount of collected waste toner in waste toner container 127 may be used. For example, any method can be used, such as determining the weight of the waste toner container or determining the amount of toner collected in the container based on the electrostatic capacitance inside the toner container. Furthermore, the amount of waste toner may be determined in any unit that can be compared with the amount of toner that can be stored, and may be determined not only by weight but also by volume, or may be based on the ratio of stored toner to the amount that can be stored.

[Judgement to start printing preparation]
With the above-described configuration, an embodiment of the present invention will be described in which, after the controller unit 201 notifies the engine control unit 202 of a pre-command indicating the start of print preparation, the engine control unit 202 determines whether to start print preparation based on the amount of collected waste toner.

FIG. 4 illustrates the flow from the standby state in which the engine control unit 202 waits for the start of printing to the start of print preparation. When the engine control unit 202 receives a pre-command from the controller unit 201 (S401), it determines whether the total amount of collected waste toner W at that time is less than a threshold (S403). In this embodiment, the threshold is set to 80%. However, the threshold is not limited to this; an appropriate value may be set depending on the device configuration, from the perspectives of preventing toner overflow and reducing FPOT. If the total amount of collected waste toner W is less than the threshold, the engine control unit 202 immediately starts print preparation (S405) without delay from the timing of receiving the pre-command, and terminates the process. Note that the term "immediately" here refers to a comparison with the case in which print preparation is started after a delay from receiving the pre-command to prevent excessive rotation when the amount of collected toner is equal to or greater than the threshold. This does not exclude a slight delay from receiving the pre-command due to the specifications and performance range of the engine control unit. Since the engine control unit does not need to consider toner overflow when the total amount of collected waste toner is less than the threshold, it can issue a command to start print preparation before the preparation process is completed and execute the preparation parallel operation. On the other hand, if the total amount of collected waste toner is equal to or greater than the threshold, it is preferable to issue an instruction to start print preparation simultaneously with or after the preparation process is completed, taking into consideration the possibility of toner overflow.

On the other hand, if the total amount of collected waste toner W is equal to or greater than the threshold in S403, the engine control unit 202 waits to receive a print instruction notified by the controller unit 201 after image development is complete (S404), and when the print instruction is received, starts print preparation (S405) and ends the process. In other words, if the amount is equal to or greater than the threshold, the start of print preparation is not instructed immediately, but rather after an interval. Note that when the controller unit 201 issues a print instruction without issuing a pre-command, this is the case shown in the timing chart of Figure 3A. In this case, print preparation is started via S401, S402, and S405, and the process ends.

As explained above, in this embodiment, if the amount of collected waste toner is less than the threshold when the engine control unit 202 receives the pre-command, it starts print preparation to shorten the FPOT. On the other hand, if the amount of collected waste toner is equal to or greater than the threshold, it controls the engine so that print preparation does not start when the pre-command is received, in order to eliminate excess rotation that generates waste toner, and prioritizes preventing overflow of the waste toner collection container. This allows the FPOT to be shortened when the cartridge is being used in a way that generates relatively little waste toner, and when waste toner generation is increasing, it prioritizes preventing waste toner over shortening the FPOT, allowing the cartridge to be used for a longer period of time.

Example 2
In the first embodiment, a control for determining whether to start a print preparation operation when a pre-command is received is described based on the total amount of collected waste toner in the waste toner container. In the second embodiment, a control for determining the timing to start a print preparation operation after a pre-command is received based on the total amount of collected waste toner is described. This allows the balance between the priority of reducing the FPOT and preventing waste toner overflow to be gradually changed based on the usage status of the cartridge as the total amount of collected waste toner increases. Below, a description of the same configuration as in the first embodiment is omitted.

[Judgement to start printing preparation]
5 shows a flow from the standby state in which the engine control unit 202 waits for the start of printing to the start of print preparation. When the engine control unit 202 receives a pre-command from the controller unit 201 (S501), it starts measuring the elapsed time since the pre-command was received (S503). Thereafter, it determines the print preparation start permitted time (Tstart) shown in Table 1 based on the total amount of collected waste toner W at that time. Note that a table showing the relationship shown in Table 1 may be stored in, for example, a storage device of the information processing device functioning as the engine control unit 202. The relationship between the total amount of waste toner and Tstart is not limited to the table below. Furthermore, the relationship may be stored in the form of a mathematical formula rather than a table.

When the time Tstart has elapsed (S505), the engine control unit 202 starts print preparation operations (S507) and ends the process. While waiting for the time Tstart to elapse (S505), the engine control unit 202 also waits for the receipt of a print instruction notified by the controller unit 201 after image development is complete (S506), and when the print instruction is received, starts print preparation (S507) and ends the process.

Note that when the controller unit 201 issues a print instruction without issuing a pre-command, this is the case shown in the timing chart in Figure 3(a). In this case, print preparation begins via S501, S502, and S507, and processing ends.

As explained above, in this embodiment, the engine control unit 202 determines the time to start print preparation based on the amount of collected waste toner when it receives a pre-command. The smaller the amount of collected waste toner, the shorter the time; the greater the amount of collected waste toner, the longer the time. Then, after the determined time has elapsed, print preparation begins to shorten the FPOT. Then, the greater the amount of collected waste toner, the more control is exercised to delay the start of print preparation based on the reception of the pre-command, in order to eliminate excess rotation that generates waste toner, and prioritize preventing overflow of the waste toner collection container. This allows the FPOT to be shortened when the cartridge is used in a manner that generates a relatively small amount of waste toner, and when waste toner generation increases, the cartridge can be used for a longer period of time by prioritizing waste toner overflow prevention over FPOT reduction in multiple stages depending on the amount of waste toner generated.

Example 3
In the first embodiment, the control for determining whether to start the print preparation operation when a pre-command is received is described based on the total amount of collected waste toner in the waste toner container. In the third embodiment, the control for determining whether to start the print preparation operation after receiving a pre-command is described, taking into consideration not only the total amount of collected waste toner but also the amount of toner consumed by the toner formed on the photosensitive drum. This allows the FPOT reduction control to continue when there is a high possibility that the toner before formation will run out before the waste toner container overflows. Below, the same configuration as in the first embodiment will not be described.

[Toner Consumption Detection]
The toner consumption detection used in this embodiment will now be described. Similar to the detection of the amount of collected waste toner in the first embodiment, the toner consumption detection is predicted based on pixel signal values sent from the pixel signal counting unit 224 to the engine control unit 202. The toner consumption is calculated by predicting the amount of toner consumed by fog toner generated during periods when image formation is not taking place and the amount of toner consumed by toner images and fog toner generated based on image data during periods when image formation is taking place, and then adding these toner consumption amounts together. This calculation process can be performed by an information processing device or processing circuit, such as the engine control unit 202, provided in the image forming apparatus 100. In this case, the engine control unit 202 functions as a consumption detection unit that detects the cumulative amount of toner consumed.

The definitions of the printing period and non-printing period are the same as in Example 1. During the printing period, of the toner consumption amount generated per page, the toner consumption amount (Cdt) due to the toner image based on the image data is calculated using formula (6), and the toner consumption amount (Cbg) due to fog toner is calculated using formula (7).

Cdt=P×D…(6)
Here, P and D are as follows:
P: the number of pixels sent from the pixel signal counting unit 224 to the engine control unit 202 (same as equation (1)).
D: Amount of toner consumed during printing per pixel formed with toner on the drum surface.
This is a predetermined value, expressed in units of [%/pixel].

Cbg=(TP)×E…(7)
where T and E are as follows:
T: The total number of pixels during the image formation period. It is determined by the drum rotation distance [mm] during the printing period and the number of pixels per predetermined drum rotation distance [pixels/mm] (same as formula (2)).
E: Amount of toner consumed during printing per pixel where no toner is formed on the drum surface. This is a predetermined value expressed in units of [%/pixel].

During non-printing periods, the amount of toner consumed (Crt) according to the rotation distance of the photosensitive drum is calculated using formula (8). Here, the unit of toner consumption is %, and 100% is when all the toner that can be formed on the photosensitive drum has been consumed.

Crt=L×F…(8)
Here, L and F are as follows:
L: drum rotation distance [mm] (same as formula (3))
F: Amount of toner consumed during a non-printing period per distance on the drum surface where no toner is formed. This is a predetermined value, and the unit is [%/mm].

From these toner consumption amounts, the toner consumption amount per job (Cjob) is calculated using formula (9) each time a print job is executed, and the total toner consumption amount (C) since the cartridge was new is calculated using formula (10). The value of this total toner consumption amount (C) is also recorded in non-volatile cartridge memory (not shown).

Cjob=Cdt+Cbg+Crt...(9)

C=C+Cjob...(10)
However, C<=100[%]

[Determining when to start print preparation]
6 shows a flow from the standby state in which the engine control unit 202 waits for the start of printing to the start of print preparation. When the engine control unit 202 receives a pre-command from the controller unit 201 (S601), it determines whether the total amount of collected waste toner W at that time is less than a threshold value (X) (S603). In this embodiment, the threshold value X is set to 80%. If the total amount of collected waste toner W is less than the threshold value X, the engine control unit 202 starts print preparation at the timing of receiving the pre-command (S605) and ends the process. Note that the value of the threshold value X is not limited to this example.

On the other hand, if the total amount of collected waste toner W is equal to or greater than the threshold value X in step S603, the engine control unit 202
It is determined whether the total toner consumption amount C at that time is less than a threshold value (Y) (S606). In this embodiment, the threshold value Y is set to 90%. Note that the value of the threshold value Y (second threshold value) is not limited to this example.

If the threshold Y is exceeded, the engine control unit 202 starts print preparation when the pre-command is received (S605) and ends the process. If the threshold Y is less than the threshold Y, the engine control unit 202 waits to receive a print instruction notified by the controller unit 201 after image development is complete (S604), and when the print instruction is received, starts print preparation (S605) and ends the process. Note that if the controller unit 201 issues a print instruction without issuing a pre-command, this is the case shown in the timing chart in Figure 3(a), and in this case, print preparation begins via S601, S602, and S605 and ends the process.

As explained above, in this embodiment, if the amount of collected waste toner is less than a predetermined threshold and the total toner consumption is equal to or greater than a predetermined threshold when the engine control unit 202 receives a pre-command, it starts print preparation to shorten the FPOT. In other cases, to eliminate excess rotation that generates waste toner, it controls the engine so that print preparation does not start when the pre-command is received, and prioritizes preventing overflow of the waste toner collection container. This makes it possible to shorten the FPOT when the cartridge is being used in a way that generates relatively little waste toner or when the amount of usable toner is running low. When waste toner generation is increasing, it prioritizes preventing waste toner over shortening the FPOT, allowing the cartridge to be used for a longer period of time.

In addition, in preventing waste toner overflow as in Example 3, it is also possible to combine the determination of the print preparation start time (Tstart) based on the amount of waste toner, as in Example 2. In this case, it is recommended to determine Tstart based on the amount of waste toner before starting print preparation in step S605.

According to each of the above embodiments, the FPOT can be shortened when the cartridge is used in a situation where waste toner generation is relatively low, and when waste toner generation is increasing, preventing waste toner overflow is prioritized over shortening the FPOT, allowing the cartridge to be used for a longer period of time. As a result, an image forming apparatus can be provided that shortens the FPOT while preventing waste toner overflow. Furthermore, considering that the period from when an image is formed in the FPOT until the recording material is ejected is approximately constant, the present invention can provide an image forming apparatus that shortens the time from user instructions to image formation while preventing waste toner overflow.

The present invention can also be understood as follows. That is, the cumulative amount of waste toner collected in the waste toner container is considered to be a first amount and a second amount that is less than the first amount. In this case, according to the present invention, even when printing the same image, the FPOT when the waste toner is the first amount will be longer than the FPOT when the waste toner is the second amount.

100: Image forming device, 122: Photosensitive drum, 125: Developer, 127: Waste toner container, 150: Process cartridge, 201: Controller, 202: Engine control unit

Claims (12)

a process cartridge including: an image carrier configured to form an electrostatic latent image on its surface in accordance with image data; a developing roller that supplies toner to the image carrier and develops the electrostatic latent image to form a toner image on the image carrier, the developing roller being in contact with the image carrier; recovery means that recovers residual toner, which is the toner that remains without being transferred from the image carrier; and storage means that stores the recovered residual toner;
a control means for causing the process cartridge to start preparation for printing and for causing the process cartridge that has completed preparation for printing to start a printing operation;
an image processing means for performing a preparatory process for the image data, which instructs the control means to start the print preparation, and after the preparatory process is completed, instructs the control means to start the print operation;
and
the control means causes the process cartridge to start the printing operation when the print preparation of the process cartridge is completed and an instruction to start the printing operation is output from the image processing means,
a collected amount detecting means for detecting an accumulated collected amount of the residual toner stored in the storing means;
When the control means receives an instruction to start the print preparation from the image processing means, the control means compares the accumulated collected amount of the remaining toner detected by the collected amount detection means with a predetermined threshold, and if the accumulated collected amount is equal to or greater than the threshold, delays the timing of starting the print preparation compared to when the accumulated collected amount is less than the threshold. 2. The image forming apparatus according to claim 1, wherein the image carrier and the developing roller are always in contact with each other. 3. The image forming apparatus according to claim 2, wherein the print preparation includes rotational driving of the image carrier. 4. The image forming apparatus according to claim 1, wherein the control unit issues an instruction to start the print preparation before the preparation process is completed if the accumulated amount of the remaining toner collected is less than the threshold value. 5. The image forming apparatus according to claim 4, wherein the control unit issues an instruction to start the print preparation simultaneously with or after the preparation process is completed when the cumulative collected amount of the remaining toner is equal to or greater than the threshold value. The image forming apparatus according to any one of claims 1 to 5, characterized in that, when the cumulative amount of recovered residual toner is equal to or greater than the threshold value, the control unit delays the timing at which the process cartridge starts the printing preparation the greater the cumulative amount of recovered residual toner. 7. The image forming apparatus according to claim 1, wherein the collected amount detection means detects the accumulated collected amount by calculating the amount of remaining toner generated during a non-printing period when the image carrier is rotating and the printing operation is not being performed, and the amount of remaining toner generated during a printing period when the printing operation is being performed. 8. The image forming apparatus according to claim 7, wherein the collected amount detection means calculates the amount of remaining toner during the non-printing period based on the rotation distance of the image carrier and the amount of remaining toner per rotation distance, and calculates the amount of remaining toner during the printing period based on the amount of remaining toner based on the number of pixels in the area where the electrostatic latent image is formed on the image carrier and the amount of remaining toner resulting from fog toner generated during the printing period. The toner supplying device further includes a consumption amount detecting means for detecting an accumulated consumption amount of the toner supplied to the image carrier,
An image forming apparatus according to any one of claims 1 to 8, characterized in that when the cumulative consumption amount of toner detected by the consumption amount detection means exceeds a second threshold, the control means causes the process cartridge to start the printing preparation immediately upon receiving an instruction to start the printing preparation from the image processing means, regardless of the cumulative recovered amount of remaining toner detected by the recovered amount detection means. 10. The image forming apparatus according to claim 9, wherein the consumption amount detection means detects the cumulative consumption amount by calculating the amount of toner consumed during a non-printing period when the image carrier is rotating and the printing operation is not being performed, and the amount of toner consumed during a printing period when the printing operation is being performed. 11. The image forming apparatus according to claim 10, wherein the consumption detection means calculates the amount of toner consumed during the non-printing period based on the rotation distance of the image carrier and the amount of toner consumed per rotation distance, and calculates the amount of toner consumed during the printing period based on the amount of toner consumed based on the number of pixels in the area where the electrostatic latent image is formed on the image carrier and the amount of toner consumed due to fog toner generated during the printing period. An image forming apparatus that receives an external instruction to form an image on a recording material and discharges the image,
a process cartridge including: an image carrier on whose surface an electrostatic latent image is formed in accordance with image data; a developing unit that supplies toner stored inside to the image carrier by a developing roller to develop the electrostatic latent image; a recovery unit that recovers residual toner, which is the toner that remains without being transferred from the image carrier to the recording material; and a storage unit that stores the recovered residual toner;
When the printout time is defined as the time from receiving the external instruction to discharging the recording material on which the image is formed, the printout time when the amount of remaining toner contained in the storage means is a first amount is longer than the printout time when the amount of remaining toner contained in the storage means is a second amount that is less than the first amount, even when the same image is printed.