JP2006323151A - Image forming apparatus, cartridge, storage device and developer supply method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus where the supply amount of toner in printing at a high printing ratio is controlled to amount by which complete stirring and charging are performed and also the amount of toner in a developing container is always kept constant so as to simultaneously settle conflicting requirements, and to provide a cartridge, a storage device and a developer supply method. <P>SOLUTION: The image forming apparatus has: a developer supply means for supplying the developer to a developing device; a means for measuring a printing ratio when forming an image; a means for calculating the amount t1 of consumed developer when forming the image from the printing ratio; a means for calculating an integrated value t2 by integrating the amount t1 of consumed developer; and a means for judging whether or not the developer is supplied to the developing device by using the integrated value t2. When the integrated value t2 shows t2>t3 to a supply threshold t3, the developer supply means is operated, and the supply threshold t3 is subtracted from the integrated value t2. The supply threshold t3 is varied in accordance with the condition of the developing device. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a copying machine equipped with a developing device that forms a latent image on an image carrier by, for example, electrophotography, and develops the latent image on a developer carrier that carries and transports the developer to form a developer image. More specifically, the present invention relates to a cartridge, a storage device, and a developer replenishing method.

  Conventionally, as a developing device used in an image forming apparatus, along with a two-component developing method using a two-component developer including a toner and a carrier as a developer, recently, a simple structure such as a magnetic toner is used. There has also been an increase in one-component developing systems using a one-component developer. In addition, many one-component replenishing systems that replenish toner with a one-component developing system have been proposed from the viewpoint of long life and reduced running costs.

  The one-component replenishment method is advantageous in that it requires less toner replenishment control than the two-component method because the amount of toner in the developing container is large.

  In such a replenishment type developing device, the toner consumed in the image formation is replenished by the toner replenishing means so that the toner amount in the developing container is controlled to be substantially constant. As a means of keeping the toner amount in the developing container constant, a method such as providing a valve in the developing container to mechanically drop the insufficient amount of toner, or providing a toner level sensor in the developing container and based on the detection result A method of replenishing them is proposed.

  For example, as described in Patent Documents 1 and 2 and the like, a toner replenishing method using a video count has been put into practical use. In this method, the output level of the output image is obtained by integrating the output level of the digital image signal for each pixel, and the amount of toner consumed is calculated and replenished.

  FIG. 18 shows a schematic configuration of a conventional image forming apparatus.

  In this example, the image forming apparatus 100 has a drum-shaped electrophotographic photosensitive member (hereinafter, referred to as “photosensitive drum”) 51 as an image carrier that is rotatably supported in an arrow direction at a substantially central portion thereof. Yes. When the image forming operation starts, the charging unit 52 uniformly charges the surface of the photosensitive drum 51, and for example, a laser irradiation unit 53 performs exposure corresponding to the image information as an exposure unit, and an electrostatic latent image is formed on the surface of the photosensitive drum 51. Is formed.

  This electrostatic latent image is then visualized by the developing device 4 to form a toner image. Next, the toner image is electrostatically transferred onto the recording material P by a transfer electric field formed between the photosensitive drum 51 and the transfer roller 56 by a transfer roller 56 as a transfer unit, for example. Thereafter, the unfixed toner image on the recording material P is permanently fixed on the recording material P by heat and pressure by the fixing device 58.

  Further, residual toner remaining on the surface of the photosensitive drum 51 after the transfer of the toner image is removed by, for example, a cleaning device 57 including a blade-shaped cleaning member, and the photosensitive drum 51 can continue to form an image. Become.

  The developing device 4 regulates the amount of the developer on the developing roller 11, a developing container 10 that stores the developer, a developing roller 11 that is a developer carrying member, a supply roller 13 that supplies the developing roller 11 with the developer. And a stirring member 15 that stirs the developer in the developing container. A developer replenishing device 5 is provided above the developing container 10. When the toner in the developing container 10 is low, a necessary amount of toner is replenished from the replenishing device 5 so that the toner amount in the developing container 10 is always constant. It is the composition kept to.

  Next, a toner replenishing method based on video count measurement will be described with reference to FIGS. 15, 16, and 17. FIG. 15 is a block diagram of an apparatus configuration for acquiring the video count number, FIG. 16 is an explanatory diagram when acquiring the video count number, and FIG. 17 is a flowchart for explaining the toner supply operation.

  In the image forming apparatus of FIG. 18, the exposure device 53 is a laser scanner device, and includes a semiconductor laser (not shown), a rotating polygon mirror, a lens, and the like. The laser light emitted from the semiconductor laser is swept by a rotating polygon mirror, and is spot-imaged on the photosensitive drum 51 by a lens such as an f / θ lens and a fixed mirror that directs the laser light toward the photosensitive drum 51 as an image carrier. The Thus, the laser beam scans the drum in a direction (main scanning direction) substantially parallel to the rotation axis of the photosensitive drum 51 to form an electrostatic latent image.

  Referring to FIG. 15, an image to be an electrostatic latent image enters a pulse width modulation circuit 32 via an image signal processing circuit 31 from a personal computer or an image input scanner, and corresponds to the level of each input pixel image signal. A laser drive pulse having the width (time length) is formed and output to the exposure device 53. That is, as shown in FIG. 16A, a wider driving pulse W is applied to a high density pixel image signal, and a narrower driving pulse S is applied to a low density pixel image signal. For the medium density pixel image signal, a driving pulse I having an intermediate width is formed.

  The laser drive pulse output from the pulse width modulation circuit 32 is supplied to the exposure device 53 and causes the semiconductor laser to emit light for a time corresponding to the pulse width. Therefore, the semiconductor laser is driven for a longer time for a high density pixel and is driven for a shorter time for a low density pixel. Therefore, the photosensitive drum 51 is exposed in a long range in the main scanning direction for high density pixels, and is exposed in a short range in the main scanning direction for low density pixels. That is, the dot size of the electrostatic latent image is different according to the pixel density. Therefore, as a matter of course, the toner consumption for the high density pixel is larger than that for the low density pixel. Note that the electrostatic latent images of the low, medium, and high density pixels in FIG. 16B are denoted by L, M, and H, respectively.

  The output signal of the pulse width modulation circuit 32 is supplied to one input of an AND gate 34, and the other input of the AND gate 34 has a clock pulse from the clock pulse oscillator 35 (pulse shown in FIG. 16C). Is supplied. Therefore, from the AND gate 34, as shown in FIG. 16A, the number of clock pulses corresponding to the pulse width of each of the laser driving pulses S, I, and W, that is, the number of clocks corresponding to the density of each pixel. A pulse is output. The number of clock pulses is accumulated by the counter 36 for each image and supplied to the CPU 37 to calculate the video count number. The image printing ratio (exposure area / paper area) is calculated from the video count number, that is, the exposure area. The amount of toner consumed at the time of image formation has a substantially linear relationship with the image printing ratio. Therefore, the toner amount considered to be consumed based on the image printing ratio is predicted, and the replenishment driving device 38 is driven for a necessary time. Replenish.

  With reference to FIG. 17, the flow of the toner replenishing operation of the conventional image forming apparatus will be described.

  After the power of the apparatus main body 100A of the image forming apparatus 100 is turned on (S1), when a predetermined start-up preparation is completed, the apparatus enters a standby state (S2). When the print signal is received in the standby state, the printing operation is started (S3), and the photosensitive drum, the charging device, the developing device, etc. are sequentially activated (S4). The exposure apparatus operates to form a latent image at the time when each apparatus settles, and acquisition of video (pixel) count data is started at the same time. When the latent image formation is completed, the exposure apparatus is stopped, and at the same time, the video count integration is completed and the video count value is acquired (S5 to S7).

  The CPU 37 that controls the operation of the image forming apparatus calculates the amount of toner consumed, that is, the amount of toner to be replenished, based on the video count value for each image formation, and replenishes the toner (S8, S9).

  Then, it is determined whether or not the job has been completed (S10). If there is a continuous print that has not been completed yet, the process returns to step 5 (S5), and the image forming apparatus enters the next cycle again. Activate the exposure apparatus. If there is no remaining number of jobs, each apparatus is stopped in order to finish the image forming operation (S10), and the process returns to step 2 (S2) to enter a standby state.

  FIG. 12 is a graph showing the relationship between the image printing ratio and the consumed toner amount. The image printing ratio and the consumed toner amount are substantially proportional. In order to keep the amount of toner in the developing container constant, the amount of toner to be replenished may be the same as the amount of consumed toner. The straight line in FIG. 13 is a graph showing the relationship between the image printing ratio and the amount of toner to be replenished.

  By using the above linear relationship, the toner amount to be replenished can be calculated from the video count number.

  If the video count is small, the amount of toner consumed is small, so the toner replenishment mechanism is driven for a short time to supply a small amount of toner. If the video count is large, the amount of toner consumed is large, so the toner replenishment mechanism drive time Add more toner for a longer time.

By adopting such a configuration, the toner amount corresponding to the consumed toner amount is replenished at an appropriate timing, and the toner amount in the developing container can be kept constant at all times.
JP-A-5-88554 JP-A-8-146636

  However, there are cases where the following problems occur in the above-described operation.

  When image formation with a high printing ratio such as a solid black image is performed, a large amount of toner is consumed, and the amount of toner replenished accordingly increases. When a large amount of new toner is replenished in the developing container, there is no particular problem as long as the charging capability of the developing device is sufficient. However, when the durability of the developing device has progressed and each component has deteriorated, or when the chargeability of the toner has decreased in a high-temperature and high-humidity environment, etc., if a large amount of new toner is replenished in the developing container, Sufficient stirring and charging cannot catch up, and fogging and toner scattering may occur.

  When the relationship between the image printing ratio and the replenishment toner amount is a straight line as in Example 1 of FIG. 14, the toner replenishment amount at the high print ratio portion where the print ratio is about 70 to 100% is charged by the developing device. In some cases, the application ability exceeded the fogging and toner scattering.

  Accordingly, the relationship between the image printing ratio and the replenishment toner amount is reviewed, and a method of setting the inclination of the linear table slightly as shown in Example 2 of FIG. 14 or the replenishment toner amount of the high print portion as shown in Example 3 is set. It is also known to take a method of adjusting the replenishment amount to be lower than the straight line in Example 1.

  10 and 11 show the transition of the toner replenishment amount and the toner amount in the developing container when the printing ratio is changed between 5% and 100% every 100 sheets and 1000 sheets are printed. 5 is a graph shown for Examples 1, 2, and 3.

  Further, the target toner amount (target value) in the developing container is set to 150 g, the toner level low warning is output by the optical sensor at 130 g, and the toner level HI warning is output at 170 g, so that the toner amount return sequence is executed.

  As understood with reference to Table 1, in Example 1, an amount of toner equal to the amount of consumed toner is replenished each time, so that the toner in the developing container does not decrease as shown in FIG. However, there is a concern that the amount of toner replenished at the time of high printing may cause a problem of fogging or toner scattering.

  In the cases of Example 2 and Example 3, since the toner replenishment amount at the time of high printing is adjusted to be small, it is possible to suppress the occurrence of fogging and toner scattering even at the time of high printing. However, the toner amount in the developing container gradually decreases because the toner replenishment amount at the time of high printing is insufficient, and the toner low warning in the developing container is erroneously turned on, or the toner amount return sequence, etc. You have to run it frequently.

  As described above, there is a problem that sufficient stirring and charging cannot be performed due to the addition of a large amount of toner during high printing, and the amount of toner in the developing container can be reduced by accurately adding the required amount of toner. It was a very difficult task to solve the requirement to keep constant at the same time.

  Therefore, the object of the present invention is to control the replenishment amount at the time of high printing to an amount capable of sufficient stirring and charging, and also to keep the developer amount in the developing container constant at the same time, simultaneously solving conflicting demands. An image forming apparatus, a cartridge, a storage device, and a developer replenishing method are provided.

The above object is achieved by the image forming apparatus, cartridge, storage device, and developer supply method according to the present invention. In summary, according to the first aspect of the present invention,
A developing device;
Developer supplying means for supplying developer to the developing device;
Means for measuring the printing ratio during image formation;
Means for calculating a consumed developer amount t1 at the time of image formation from a print ratio;
Means for integrating the consumed developer amount t1 to calculate an integrated value t2,
Means for determining whether or not it is necessary to replenish the developer to the developing device using the value of the integrated value t2.
In an image forming apparatus having
The integrated value t2 is greater than the supply threshold t3.
t2> t3
An image forming apparatus that operates the developer replenishing means to subtract the replenishment threshold value t3 from the integrated value t2.
The replenishment threshold value t3 is variable according to the state of the developing device.

According to a second aspect of the invention,
A developer replenishing method for an image forming apparatus, comprising: a developing device; a replenishing unit for replenishing the developer to the developing device; and a unit for measuring a printing ratio during image formation.
A first calculation step of calculating the developer consumption during image formation based on the print ratio;
A second calculation step of calculating the integrated value by integrating the developer consumption amount;
A replenishing step of replenishing the developer with the developer by operating the replenishing unit once when the integrated value is greater than a predetermined threshold;
A third calculation step of subtracting the threshold value from the integrated value after the replenishment step;
Changing the threshold according to the state of the developing device;
A developer replenishing method is provided.

According to a third aspect of the invention,
A cartridge detachably attachable to an image forming apparatus having a replenishing means for replenishing a developer and a means for measuring a printing ratio during image formation;
A developing device for storing the developer, and storage means for storing information;
The storage means stores a storage area for storing information related to an integrated value of developer consumption during image formation calculated based on the print ratio;
A storage area for storing information relating to a threshold for controlling the operation of the replenishing means;
A storage area for storing information for correcting the threshold;
There is provided a cartridge characterized by comprising:

According to a fourth aspect of the invention,
A storage device mounted on a cartridge used in an image forming apparatus having a replenishing means for replenishing a developer and a means for measuring a printing ratio during image formation,
A storage area for storing information relating to an integrated value of developer consumption during image formation calculated based on the print ratio;
A storage area for storing information relating to a threshold for controlling the operation of the replenishing means;
A storage area for storing information for correcting the threshold;
A storage device is provided.

  According to the present invention, by changing the replenishment threshold value t3 according to the environmental information, it is possible to sufficiently charge the replenished developer even under various environments, and to eliminate the shortage of developer due to high printing. Can be achieved. Further, by changing the replenishment threshold t3 according to the life of the developing device, the replenished developer can be sufficiently charged even if each part of the developing device deteriorates, and there is no developer shortage due to high printing. Can be achieved. Therefore, by selecting a replenishment threshold t3 as large as possible according to the state of the developing device, it is possible to always obtain a high-quality image without being covered and without fear of lack of developer in high-printing printing. .

  Hereinafter, an image forming apparatus, a cartridge, a storage device, and a developer supply method according to the present invention will be described in more detail with reference to the drawings.

Example 1
FIG. 1 shows a schematic configuration of an embodiment of an image forming apparatus according to the present invention. Since the image forming apparatus 100 of the present embodiment has the same configuration as that of the image forming apparatus 100 described above with reference to FIG. 18, members having the same configuration and function are denoted by the same reference numerals. The detailed description is omitted.

  That is, in this embodiment, the image forming apparatus 100 includes a drum-shaped electrophotographic photosensitive member, that is, a photosensitive drum 51 as an image carrier that is rotatable in the arrow direction. When the image forming operation starts, the charging unit 52 uniformly charges the surface of the photosensitive drum 51, and for example, a laser irradiation unit 53 performs exposure corresponding to the image information as an exposure unit, and an electrostatic latent image is formed on the surface of the photosensitive drum 51. Is formed. The configuration for obtaining the video count by the image signal processing means is the same as that of the image signal processing means included in the conventional image forming apparatus described with reference to FIGS. Therefore, the description of the exposure unit and the image processing unit in the present embodiment uses the above description, and the description thereof is omitted here.

  The electrostatic latent image on the photosensitive drum 51 is visualized by the developing device 4 to be a visible image, that is, a toner image. This toner image is transferred onto the recording material P by a transfer roller 56 as transfer means, for example. Thereafter, the unfixed toner image on the recording material P is permanently fixed on the recording material P by heat and pressure by the fixing device 58.

  Further, the transfer residual toner remaining on the surface of the photosensitive drum 51 after the transfer of the toner image is removed by, for example, a cleaning device 57 provided with a blade-shaped cleaning member, and the photosensitive drum 51 can continue to form an image. .

  The developing device 4 includes a developing container 10 that stores the developer D, a developing roller 11 that is a developer carrying member, a supply roller 13 that supplies the developing roller 11 with the developer, and a developer amount on the developing roller 11. It has a developer layer thickness regulating member 14 for regulating, and an agitating member 15 for agitating the developer in the developing container. The developer D used in this embodiment is a negatively charged nonmagnetic one-component developer (hereinafter referred to as “toner”).

  A developer replenishing device 5 is provided above the developing container 10. When the toner in the developing container 10 is low, a necessary amount of toner is replenished from the replenishing device 5 so that the toner amount in the developing container 10 is always constant. It is made the composition to keep in.

  Next, the schematic configuration of the developing device 4 according to the present embodiment and the configuration in the vicinity thereof will be described in more detail.

According to the present embodiment, the developing container 10 is partially open on the side facing the photosensitive drum 51, and the developing roller 11 as a developer carrying member is exposed in the direction of the arrow so as to be partially exposed from the opening. The developer container 10 is rotatably supported and is in contact with the photosensitive drum 51 with a predetermined contact pressure. The developing roller 11 has an outer diameter constituted by a low hardness rubber material or foam such as silicone or urethane having a volume resistivity of 10 ² Ωcm to ^{10 10} Ωcm in which a conductive agent such as carbon is dispersed, and a combination thereof. This is a 16 mm semiconductive elastic roller.

  The supply roller 13 as a developer supply and recovery means is an elastic roller made of sponge and having an outer diameter of 16 mm, and is disposed in contact with the development roller 11.

  An agitating paddle 15 as a developer agitating / conveying means is provided in the inner part opposite to the opening of the developing container 10 so as to be rotatable in the direction of the arrow. The toner is conveyed to a region near the contact portion with the supply roller 13. As the supplied toner 13 rotates in the direction of the arrow, the conveyed toner is charged with toner due to frictional charging accompanying sliding friction with the developing roller 11 in contact therewith. The charged developer is supplied onto the developing roller 11 by receiving a reflection force from the developing roller 11 due to the charged charge.

  The developing container 10 is provided with a blade 14 as a developer layer thickness regulating member so as to pressurize the developing roller 11. The blade 14 is a leaf spring made of SUS, and abuts against the developing roller 11 with a predetermined abutment pressure while being bent within an elastic range. The toner supplied onto the developing roller 11 is subjected to layer thickness regulation and electric charge by the blade 14 to form a thin layer of toner on the developing roller 11 and supplied to the developing region.

  The toner that does not contribute to the development and is still carried on the developing roller 11 is peeled off from the developing roller 11 by rubbing by the supply roller 13, and a part of the toner is newly supplied onto the supply roller 13. The supplied toner 13 is again supplied onto the developing roller 11 by the supply roller 13, and the rest is returned to the developing container 10.

  In this embodiment, the supply roller 13 has two functions as the developer supply and recovery means. However, the present invention is not limited to this, and the developer supply means and the developer recovery means are provided. It is also possible to provide them separately.

  The replenishing device 5 as a developer replenishing unit is configured to be detachable from the apparatus main body 100A of the image forming apparatus 100. The replenishing toner is accommodated therein, and the replenishing device 5 is replaced as needed. This is a mechanism for supplying toner to the image forming apparatus.

  Inside the replenishing device 5, a stirring member 6 for releasing the toner and a replenishing roller 7 for replenishing the toner from the replenishing device 5 to the developing device 4 are arranged. Further, the replenishing device 5 is configured to replenish the developing device 4 with a constant amount of toner per predetermined driving time by a replenishing command from the replenishing driving device 38.

  In the image forming apparatus 100 of this embodiment, the process speed, that is, the peripheral speed of the photosensitive drum 51 is 150 mm / sec, and the peripheral speed of the developing roller 11 is 225 mm / sec.

  Toner replenishment control basically uses a method based on video count, but a means for directly detecting the amount of toner is also provided in the developing container 10, so that the calculation of toner replenishment based on video count should be combined. In addition, it is possible to avoid in advance a situation in which the inside of the developing container is likely to overflow with toner, or the image is not output due to shortage.

  A stirring member 15 is provided in the developing container 10 of the developing device 4 so as to be rotatable in the direction of the arrow, and forms a stirring region for stirring the toner in the developing container 10 and the toner supplied from the replenishing device 5.

  Further, an optical toner surface detecting means 16 for detecting the height of the toner surface in the stirring region is disposed outside the developing container 10 sandwiching the stirring region. The toner surface detection means 16 includes a light emitting element 16a, a light transmitting window 16b, and a light receiving element 16c, and the ratio of the light transmission time when the toner surface Ds in the developing container changes as the stirring member 15 rotates. And the height information of the toner surface Ds in the stirring region is obtained. In this embodiment, the light detection method is used as the direct detection means 16, but a method using a piezo sensor or the like may be used.

  The image forming apparatus main body 100A is equipped with an environmental sensor 200 capable of detecting the ambient temperature and humidity, and can be converted into an absolute moisture amount from the obtained temperature and humidity values. You can recognize the environmental conditions around you.

  In this embodiment, the storage means (not shown) provided in the CPU 37, which is a control means provided in the apparatus main body 100A, stores information on the number of printed sheets, toner consumption information, and toner as life information of the developing device. Stores replenishment amount information.

According to the toner replenishment control of the present invention, the replenishment integrated value (t2) is calculated by integrating the consumed toner amount (t1) at the time of image formation calculated from the print ratio, and this replenishment integrated value (t2) is the replenishment threshold value. For (t3)
t2> t3
At this time, the toner replenishing device operates to perform toner replenishment, and the replenishment threshold value (t3) is subtracted from the integrated value (t2). At this time, the replenishment threshold value (t3) is variable based on the environmental condition around the developing device 4 and the life information of the developing device 4, or based on at least one of the information.

  Next, toner replenishment control in this embodiment will be described in detail.

  The toner replenishment control according to the present invention does not directly replenish the consumed toner amount (t1) to be replenished calculated by the video count, but temporarily stores the accumulated value (t2) as a storage unit of the CPU 37 provided in the apparatus main body 100A. To store. Further, the amount of toner replenished by one operation of the toner replenishing device is information related to the replenishment threshold value (t3) based on the combined use of the developer life information and the environment information or based on at least one of the information. After the replenishment amount correction coefficient (α) is determined, the replenishment threshold value (t3) is corrected with the correction coefficient (α), and the corrected replenishment threshold value (t4) is determined. The toner supply device is operated once when the integrated value (t2) of the toner amount to be supplied exceeds the corrected supply threshold value (t4).

Next, a list of parameters used in this example is shown below.
A: Amount of toner developed on the photosensitive drum 0.6 mg / cm ²
-S: Paper area (A4 paper size) 21.0 * 29.7cm
・ R: Image printing ratio calculated from video count 0-100%
T1: Toner amount to be replenished per sheet (= toner consumed per sheet)
t1 = A * S * R
The range that t1 can take is 0 to 374 mg.
T1max: Consumed toner amount when printing ratio R is maximum 374 mg
T2: accumulated toner amount t3: replenishment threshold (= toner amount replenished by one operation of toner replenishing device)
Α: Toner replenishment amount correction coefficient t4: Replenishment replenishment threshold (t4 = t3 * α)
-Pa: Number of prints-L: Number of developer lifespan The toner loading amount (A) and paper area (S) are numerical values that are corrected at any time by paper size detection and toner patch density detection of the image forming apparatus. However, in the study in this example, a fixed value was used in order to reduce the influencing factors.

  Here, the flow of the toner supply operation will be described with reference to the flowchart of FIG.

  After the main body of the image forming apparatus is turned on (S1), the standby state (S2) is entered when the predetermined startup preparation is completed.

  When the print signal is received in the standby state, the temperature / humidity is obtained by the environmental sensor 200 which is a temperature / humidity detecting means mounted on the main body, and is converted into an absolute moisture amount from the value to obtain an absolute moisture amount of 18.0 [g / When it is higher than g (760 mmHg)], it is regarded as a high temperature and humidity environment, and when the absolute water content is less than 5.8 [g / g (760 mmHg)], it is regarded as a low temperature and low humidity environment and environmental information is judged (S3).

  Further, in this embodiment, the number-of-printing-sheet information (Pa) stored in the memory of the CPU 37 is read (S4), and [100− (Pa * 100) is determined by the developing unit life number (L) and the current number of printed sheets (Pa). ) / L] is calculated to determine the remaining life of the developing device (S5). Then, the value (α) of the correction coefficient is determined by using the environment information indicating the state of the developing device and the developing device lifetime information in combination or using at least one of the information.

  When the correction coefficient (α) is obtained, a corrected supply threshold value (t4) obtained by multiplying the supply threshold value (t3) and the correction coefficient (α) is calculated, and the toner corresponding to the corrected supply threshold value (t4). Let the amount be the amount to be replenished in one replenishment operation (S6).

  Thereafter, the printing operation is started, and the photosensitive drum, the charging device, the exposure device, and the like are sequentially activated (S7). The exposure apparatus operates to form a latent image (S8), and the acquisition of video (pixel) count data is started at the same time as the time required for each apparatus to settle down. When the latent image formation is completed, the exposure apparatus is stopped (S9), and at the same time, the video count integration is completed and a video count value is acquired (S10).

  Based on the video count value, the CPU 37 calculates a toner replenishment amount (t1) that has been consumed, that is, should be replenished, and calculates a replenishment integrated value (t2) (S11, S12).

  Next, the replenishment integrated value (t2) and the corrected replenishment threshold value (t4) are compared (S13). If replenishment integrated value (t2) ≦ replenishment threshold value (t4), replenishment is not performed. If the replenishment integrated value (t2)> the replenishment threshold (t4), a toner replenishment of an amount corresponding to the replenishment threshold (t4) is performed once, and a replenishment threshold (t4) that is the amount replenished from the replenishment integrated value (t2). Is subtracted, and the remainder continues to be accumulated (S14, S15).

  Replenishment of the toner amount (t4) after the replenishment threshold (t3) is corrected is performed by controlling the rotation speed of the replenishment motor constituting the replenishment drive device 38.

  FIG. 4 shows the relationship between the rotation speed of the replenishment motor 38 and the replenishment amount. 400 mg of replenishment is performed by two rotations of the replenishment motor 38, and 200 mg of half is replenished by one rotation of the replenishment motor 38. Further, since 40 mg is replenished at 0.2 rotation, the target replenishment amount can be obtained by controlling the rotation speed of the replenishment motor 38 in accordance with the correction coefficient (α).

  In this embodiment, when α = 1, 400 mg of toner is replenished.

  Next, it is determined whether or not the job has been completed (S16). If there is a continuous print that has not yet been completed, the process returns to step 8 (S16), and the image forming apparatus enters the next cycle again. To operate the exposure apparatus. If there is no remaining number of jobs, each apparatus is stopped in order to complete the image forming operation (S17), and the process returns to step 2 (S2) to enter a standby state.

  By setting the corrected replenishment threshold (t4) smaller than (t1max), the replenishment amount at the time of high printing can be reduced, so that a large amount of replenishment toner is added at a time due to insufficient stirring and charging. Although it is possible to prevent fogging and the like, if the replenishment threshold (t4) is made too small, although it is advantageous for fogging due to stirring and insufficient charging, the amount that cannot be replenished during high printing increases. End up. As a result, the amount of toner in the developing container decreases, and a toner amount return sequence or the like must be performed, resulting in a decrease in printer performance.

  By the way, the maximum amount of toner that can be replenished without causing fogging varies depending on the operating state of the developing device, such as the durability and environment. This is because the absolute moisture content in the air changes due to changes in the environment, and the chargeability of the toner changes, and as the number of printed sheets increases, the parts that make up the developing device deteriorate and become toner. This is because the charge imparting ability is attenuated.

  Therefore, in order to achieve both the lack of fogging and the lack of replenishment for high printing, it is necessary to set the replenishment threshold (t3) as large as possible within a range that does not cause fogging. That is, by correcting the replenishment threshold (t3) according to durability and the environment, and setting the replenishment threshold (t3) as large as possible within a range that does not cause fogging, it is possible to achieve both the shortage of replenishment for high printing and the fogging.

  From this point of view, in order to determine the optimum replenishment amount, the fogging level when printing was performed until the lifetime of the developing device was changed by changing the correction coefficient (α) depending on the environment. The results are shown in Table 2.

  First, when the absolute moisture content is in the range of 5.8 [g / g (760 mmHg)] to 18.0 [g / g (760 mmHg)] with a cartridge in which the life of the developing device is defined as 40,000 sheets (NN) In this case, α = 0.8 for up to 20,000 sheets, which is half the life of the developing device, α = 0.7 for 20,000 to 30,000 sheets, and α = 0.6 for the remaining life, depending on the number of prints. Thus, it can be said that changing (α) step by step is the most preferable correction of the replenishment threshold t3 without fogging and without a significant decrease in the toner amount.

  When the absolute water content is less than 5.8 [g / g (760 mmHg)] (LL), since the toner is very easily charged, α = from the latter half of the developing device life (about 30,000 printed sheets). The replenishment threshold (t3) may be corrected by 0.7.

  Further, when the absolute water content is higher than 18.0 [g / g (760 mmHg)] (HH), the amount of water in the air is so large that the toner is hardly charged, and the life of the developing device It is necessary to correct the supply threshold (t3) even from the first half. Α = 0.8 may be used at the beginning of the developing device life, but correction is performed when 10,000 sheets are printed, and α = 0.7. After that, correction is executed step by step every 10,000 sheets, and in the latter half of the development life, α = 0.5 is finally set as the lower limit value of the correction coefficient. As a result, even if each part deteriorates due to printing, by controlling the replenishment level to a level at which the toner can be charged, the entire toner is easily charged even in a high-temperature and high-humidity environment with a large amount of absolute moisture.

  In this way, as shown in FIG. 3, the replenishment amount correction coefficient (α) is determined according to each environment and the remaining life of the developing device, and the post-correction replenishment threshold value (t4) is optimized, thereby achieving high quality. An image can be obtained.

  Using the configuration of this example, a durability test of 40,000 sheets, which is the durability life of the developing device, was performed, but density unevenness and fogging due to poor mixing of replenishing toner did not occur, and a good image could be maintained. It was.

  In this way, the information on the environment and the remaining life of the developing device is used in combination, and the replenishment threshold (t3) is set as large as possible within the range that does not fog, so that replenishment is possible even in any environment and at the end of the developing device life. Since it is possible to easily charge the applied toner uniformly, fogging can be suppressed and the toner consumption of the developing device can be suppressed. In addition, the state in which the toner amount in the developing device is greatly reduced even temporarily can be reduced.

  Therefore, there is a problem that sufficient stirring and charging cannot be performed when a large amount of toner is added during high printing, and the amount of toner in the developing device is always kept constant by accurately adding the required amount of toner. It is possible to solve the demands simultaneously, solve the problem of toner replenishment according to environmental differences and the problem of uncharged toner due to deterioration of each part, and obtain high quality images throughout the life of the developing device. .

  In this embodiment, the correction coefficient (α) is set according to the rotation speed of the replenishment motor 38. However, the correction coefficient (α) is not limited to this, and may be set more finely according to the performance of the replenishment motor 38. However, in the case of a developing device having a long life, the correction coefficient (α) may be set larger.

  In this embodiment, the number of printed sheets is used as means for judging the life of the developing device. However, the life judging method is not limited to this, and the number of rotations of the photosensitive drum may be used.

  The present embodiment can also be applied to a case where a two-component developer including a toner and a carrier is used as a developer. However, the principle of the present invention is applied to a developing device using a conventional two-component developer. In the case of application to the developer replenishment system, the amount of toner in the developing device using the two-component developer is small in the first place. It is expected to be up.

  Therefore, in this embodiment, there is a certain amount of toner in the developing container, and even if the toner amount in the developing container temporarily decreases during the formation of a high-print image, the total balance can be met by supplying it a little later. For example, since the characteristics of the developer replenishing method in the developing device using the one-component developer that is ok are used, it is desirable to use the developing device in the one-component replenishing method.

Example 2
In this embodiment, a process unit for image formation including at least a developing device is integrated with an image forming apparatus to form a removable cartridge, and a non-volatile memory is attached to the cartridge as a storage unit. Information on the number of printed sheets, toner consumption amount information, toner replenishment amount information, and the like are stored in the nonvolatile memory, and information on an integrated value (t2), a replenishment threshold value (t3), and a replenishment correction coefficient (α) is also stored. This is the feature.

  Since the schematic configuration and basic operation of the image forming apparatus of the present embodiment are the same as those of the first embodiment, the description of the first embodiment is used, and a duplicate description is omitted. Hereinafter, the cartridge constituting the characteristic part of the present embodiment will be described.

  FIG. 5 shows a schematic configuration of the cartridge used in this embodiment.

  In this embodiment, the cartridge 30 includes the photosensitive drum 51 described in the first embodiment, a charging roller 52, a developing device 4, and a cleaning device as process means acting on the photosensitive drum 51 for image formation. 17 is formed as a cartridge by being integrated with the image forming apparatus main body 100A. Of course, only the developing device can be detachably attached to the image forming apparatus as a cartridge. In particular, as the cartridge, a so-called process cartridge, in which the photosensitive drum 51 and at least the developing device 4 as the process means are integrated, is widely used.

  According to this embodiment, the cartridge 30 is provided with a storage means 39 such as a nonvolatile memory.

  FIG. 6 is a block diagram illustrating the configuration of the image forming apparatus 100 according to the present exemplary embodiment. The configuration of the image signal processing means for obtaining the video count is the same as in the first embodiment. That is, the image signal processing unit has the same configuration as that of the conventional image forming apparatus described with reference to FIGS.

  However, as shown in FIG. 6, in this embodiment, when the CPU 37 calculates the toner replenishment amount integrated value t2, the calculation is performed after reading the integrated value t2 stored in the nonvolatile memory 39 of the cartridge 30. The integrated value t2 newly calculated is overwritten and stored in the nonvolatile memory 39 as needed.

  FIG. 8 shows the storage state of the nonvolatile memory 39 of the cartridge 30. Information is written to and read from the nonvolatile memory 39 by the CPU 37 of the image forming apparatus 100. The non-volatile memory 39 is provided with a storage area. In this embodiment, the storage area 39a stores the replenishment integrated value information (t2), the storage area 39b stores the replenishment threshold information (t3), and the correction coefficient information. A storage area 39c for storing (α) is provided.

  That is, FIG. 7 shows a flowchart of the present embodiment, which is similar to the flowchart described in the first embodiment. However, in the first embodiment, the CPU 37 that controls the operation of the image forming apparatus in step 11 and step 12. However, the toner replenishment amount t1 to be replenished is calculated on the basis of the video count value for each image formation, and the replenishment integrated value t2 that is the toner replenishment amount to be replenished by integrating the toner replenishment amount t1 is calculated (S11, S12). Then, the replenishment integrated value t2 and the corrected replenishment threshold value t4 are compared (S13).

  On the other hand, in this embodiment, as shown in the figure, Step 7 and Steps 12-1 to 12-4 are provided, and the CPU 37 is based on the video count value for each image formation as in Embodiment 1. A toner supply amount t1 to be supplied is calculated (S11). On the other hand, when calculating the toner replenishment amount integrated value t2, first, the integrated value t2 accumulated until the previous image formation stored in the nonvolatile memory 39 of the cartridge 30 is read (S12-1). Further, the number of printed sheets Pa is updated to Pa ′ (S12-2), and a new replenishment integrated value t2 is calculated (S12-3). Next, a comparison is made between the latest supply integrated value t2 and the corrected supply threshold value t4 corrected using the correction coefficient information (α) stored in the nonvolatile memory (S13). The newly calculated integrated value t2 and the updated number of printed pages Pa 'are overwritten and stored in the nonvolatile memory 39 of the cartridge 30 (S12-4).

  The flow of the toner replenishment operation shown in the flowchart of this embodiment shown in FIG. 7 is the same as the flowchart described in Embodiment 1 with reference to FIG. 2 except for the operations of Step 12-1 to Step 12-4. Since it is the same as the toner replenishing operation, the same step is denoted by the same reference numeral, the description of the first embodiment is used, and the description thereof is omitted here.

  According to the present embodiment, the same operational effects as those of the first embodiment can be achieved. Further, by adopting the above configuration, the integrated value t2 that is the toner replenishment amount information in the nonvolatile memory 39, and the number of printed sheets information , Toner consumption information, etc. are always attached with the developing container. For example, the developing device is taken out from the image forming apparatus while the integrated value is being stored large during high-print image formation. Even if this happens, the developer container stores the amount of toner to be added together with the non-volatile memory. Therefore, when the developer container is set in the image forming apparatus again, a temporary shortage of the amount of toner to be added is stored. The amount of toner in the developing container can be reduced or lost.

  Thus, the replenishment control described in the first embodiment can be reliably performed even when the developing device is attached or detached.

  Further, by adopting such a cartridge form, it becomes possible to easily replace the component parts, and the maintainability of the image forming apparatus is remarkably improved. Also, by exchanging the cartridge, important components of the electrophotography are replaced with new ones, so that a high-quality image can always be maintained.

  Further, in this embodiment, different types of cartridges, for example, red and black cartridges that store different color developers, such as red cartridge and black cartridge, can have a replenishment threshold value t3 and a correction coefficient α. In the image forming apparatus, it is possible to achieve the same operational effects as in the first embodiment, and the optimum replenishment threshold value t3 and the correction coefficient α can be individually provided according to the cartridge manufacturing situation. Can be operated.

Example 3
In the present embodiment, the operation described in the second embodiment is mounted on a color image forming apparatus having a plurality of process cartridges mounted thereon. Further, the supply threshold (t3) and the supply correction coefficient (α) are stored in the nonvolatile memory of the process cartridge. ) Is memorized. Further, as in the second embodiment, the non-volatile memory can also store the number of printed sheets, toner consumption information, toner supply information, and the like.

  FIG. 9 shows an example of a color image forming apparatus of the tandem type intermediate transfer system of this embodiment. In this embodiment, the image forming apparatus 100 includes four image forming units, that is, image forming stations P (PY, PM, PC, PBk) arranged in series in the image feeding direction in the image forming apparatus main body 100A. Yes. Each image forming station P (PY, PM, PC, PBk) is a drum-shaped electrophotographic photosensitive member that is an image carrier, that is, a photosensitive drum 51 (51Y, 51M, 51C, 51Bk), and charging as a charging unit. A charging device 52 (52Y, 52M, 52C, 52Bk) as a roller, an exposure device 53 (53Y, 53M, 53C, 53Bk) as a laser beam scanner unit as an exposure unit, and a developing device 4 (4Y as a developing unit) 4M, 4C, 4Bk), a cleaning device 57 (57Y, 57M, 57C, 57Bk) having a cleaning blade as a cleaning unit, and a primary transfer device 56 (56Y) serving as a transfer roller as a primary transfer unit 56M, 56C, 56Bk).

  The photosensitive drums 51 (51Y, 51M, 51C, 51Bk), the charging device 52 (52Y, 52M, 52C, 52Bk), and the developing device 4 (4Y, 4B) constituting each image forming station P (PY, PM, PC, PBk). 4M, 4C, 4Bk) and the cleaning device 57 (57Y, 57M, 57C, 57Bk) are integrated to form a cartridge 30 (30Y, 30M, 30C, 30Bk). The cartridge 30 in the present embodiment has the same configuration as the cartridge 30 described in the second embodiment with reference to FIG.

  Further, a replenishing device 5 (5Y, 5M, 5C, 5Bk) similar to that of the first embodiment is arranged to be exchangeable with the image forming apparatus. The configurations, operations, and the like of the photosensitive drum 51, the developing device 4, the charging device 52, and the like in each process cartridge 30 have the same configurations and functions as those in the first and second embodiments. Therefore, members having the same configuration and function as the cartridge 30 and the toner replenishing device 5 performed in the first and second embodiments are denoted by the same reference numerals, and the description of the first and second embodiments is used. Description is omitted.

  The configuration of the image signal processing means for obtaining the video count has been described in the first embodiment, that is, the image signal processing means included in the conventional image forming apparatus described in FIGS. 15 and 16, and the description in FIG. Since the configuration is the same as that of the second embodiment, the description of the first and second embodiments is used, and the description thereof is omitted here.

  In the image forming apparatus of this embodiment, the photosensitive drums 51 (51Y, 51M, 51C, 51Bk) and the primary transfer devices 52 (52Y, 52M, 52C, 52Bk) of the respective image forming stations P (PY, PM, PC, PBk). The intermediate transfer belt 61, which is a belt-like intermediate transfer member, is wound around the support rollers 62a, 62b, and 63c and arranged to be movable in the direction of the arrows.

  Also in this embodiment, a light source device and a polygon mirror that constitute the exposure device 53 are installed above the image forming apparatus main body 100A, and an image is formed on the photosensitive drum 51 (51Y, 51M, 51C, 51Bk). An electrostatic latent image corresponding to the signal is formed.

  Each of the developing devices 4 (4Y, 4M, 4C, 4Bk) is filled with a predetermined amount of one-component developer made of non-magnetic toner of yellow, magenta, cyan, and black, and the developing roller 11 (11Y, 11M, 11C). , 11Bk), the latent image on the photosensitive drum 1 is sequentially developed with toner of each color to form a toner image, and is primarily transferred onto the intermediate transfer belt 61.

  Further, the transfer material P accommodated in a transfer material cassette (not shown) is conveyed to a secondary transfer roller 63 as a secondary transfer device which is a secondary transfer means, and is a toner image carried on the intermediate transfer belt 61. Is secondarily transferred to the transfer material P. The transfer material P onto which the toner image has been transferred is fixed to the toner image by heating and pressing with a fixing device (not shown) and then discharged out of the device as a full-color image.

  An intermediate transfer belt cleaning device 64 is disposed downstream of the secondary transfer position on the transfer material P in the direction of travel of the intermediate transfer belt in order to clean fog toner, secondary transfer residual toner, and the like attached to the surface of the intermediate transfer belt 61. Has been.

  On the other hand, the primary transfer residual toner or the like remaining on the photosensitive drum 51 (51Y, 51M, 51C, 51Bk) is cleaned by the photosensitive drum cleaning device 57 (57Y, 57M, 57C, 57Bk).

  In such a full-color image forming apparatus, since a multi-color image is superimposed on a sheet of paper, a level much higher than that of a monochrome model is required for fogging. The replenishing method can be more suitably used for such a full-color image forming apparatus.

  In particular, the replenishment threshold t3 and the correction coefficient α are stored in the nonvolatile memory 39 (39Y, 39M, 39C, 39Bk) of each process cartridge 30 (30Y, 30M, 30C, 30Bk), so that the replenishment unique to each developing device. The threshold value t3 and the correction coefficient α can be provided.

  Therefore, in this embodiment, the same effects as those of Embodiments 1 and 2 can be achieved. In particular, the optimum replenishment threshold value t3 and the correction coefficient α are individually provided according to the cartridge manufacturing situation, or the toner color It is possible to provide a different replenishment threshold t3 and correction coefficient α every time, and it is possible to always operate the image forming apparatus with an optimum replenishment threshold.

1 is a schematic cross-sectional view of an embodiment of an image forming apparatus according to the present invention. 3 is a flowchart illustrating an example of the operation of the image forming apparatus of the present invention. 6 is a graph showing a relationship between an environment and the number of printed sheets and an optimum correction coefficient in the image forming apparatus of the present invention. 6 is a graph showing the relationship between the replenishment motor rotation speed and the replenishment amount in the image forming apparatus of the present invention. 1 is a schematic sectional view of an example of a process cartridge used in an image forming apparatus of the present invention. 1 is a block diagram illustrating an apparatus configuration of an embodiment of an image forming apparatus according to the present invention. 6 is a flowchart of another embodiment illustrating the operation of the image forming apparatus of the present invention. It is a figure which shows the memory | storage state of the non-volatile memory provided in the cartridge of this invention. FIG. 5 is a schematic cross-sectional view of another embodiment of an image forming apparatus according to the present invention. 6 is a graph showing the relationship between the number of printed sheets and the replenishment amount in a conventional image forming apparatus. 6 is a graph showing the relationship between the number of printed sheets and the amount of toner in a developing container in a conventional image forming apparatus. It is a graph which shows the relationship between the conventional image printing ratio and a toner replenishment amount. It is a graph which shows the relationship between the conventional image printing ratio and a toner replenishment amount. It is a graph which shows the relationship between the conventional image printing ratio and a toner replenishment amount. It is a block diagram which shows the apparatus structure of the conventional image forming apparatus. It is a figure for demonstrating the conventional video count measuring method. 6 is a flowchart illustrating an operation of a conventional image forming apparatus. It is a schematic sectional view of a conventional image forming apparatus.

Explanation of symbols

4 Developing Device 5 Replenishing Device 11 Developing Roller (Developer Carrier)
13 Supply roller (developer supply and recovery means)
14 Developer Restricting Member 15 Stirring Member 30 Cartridge 37 CPU
39 Nonvolatile memory (storage means)
51 Photosensitive drum (image carrier)
52 Charging device (charging means)
57 Cleaning device 200 Environmental sensor (temperature / humidity detection means)

Claims (11)

A developing device;
Developer supplying means for supplying developer to the developing device;
Means for measuring the printing ratio during image formation;
Means for calculating a consumed developer amount t1 at the time of image formation from a print ratio;
Means for integrating the consumed developer amount t1 to calculate an integrated value t2,
Means for determining whether or not it is necessary to replenish the developer to the developing device using the value of the integrated value t2.
In an image forming apparatus having
The integrated value t2 is greater than the supply threshold t3.
t2> t3
An image forming apparatus that operates the developer replenishing means to subtract the replenishment threshold value t3 from the integrated value t2.
The replenishment threshold t3 is variable according to the state of the developing device.   The information α relating to the replenishment threshold t3 is included, and the information α relating to the replenishment threshold t3 is selected according to the state of the developing device to determine the replenishment threshold t3. The image forming apparatus described in 1.   3. The image forming apparatus according to claim 2, further comprising means for detecting temperature and humidity, wherein the information α is selected according to a result of the temperature and humidity detection means, and the value of the replenishment threshold value t3 is determined. . The image forming apparatus main body is provided with means for detecting temperature and humidity and storage means,
Storing life information of the developing device in the storage means;
The image forming apparatus according to claim 2, wherein the information α is selected according to a result of the temperature and humidity detection unit and / or the life information, and a value of the replenishment threshold value t <b> 3 is determined. An integrated cartridge having at least the developing device is attachable to and detachable from the image forming apparatus main body;
A storage means is provided in the cartridge,
Cartridge life information is stored in the storage means;
The image forming apparatus according to claim 2, wherein the information α is selected according to the cartridge life information, and the value of the replenishment threshold t3 is determined. An integrated cartridge having at least the developing device is attachable to and detachable from the image forming apparatus main body;
A storage means is provided in the cartridge,
Cartridge life information is stored in the storage means;
The image forming apparatus according to claim 3, wherein the information α is selected according to a result of the temperature / humidity detection unit and the cartridge life information, and a value of the replenishment threshold value t <b> 3 is determined.   The image forming apparatus according to claim 5, wherein the cartridge further includes an image carrier on which an image is formed.   The image forming apparatus according to claim 7, wherein a plurality of the cartridges are installed, and each of the cartridges can have a different replenishment threshold value t <b> 3. A developer replenishing method for an image forming apparatus, comprising: a developing device; a replenishing unit for replenishing the developer to the developing device; and a unit for measuring a printing ratio during image formation.
A first calculation step of calculating the developer consumption during image formation based on the print ratio;
A second calculation step of calculating the integrated value by integrating the developer consumption amount;
A replenishing step of replenishing the developer with the developer by operating the replenishing unit once when the integrated value is greater than a predetermined threshold;
A third calculation step of subtracting the threshold value from the integrated value after the replenishment step;
Changing the threshold according to the state of the developing device;
A developer replenishing method. A cartridge detachably attachable to an image forming apparatus having a replenishing means for replenishing a developer and a means for measuring a printing ratio during image formation;
A developing device for storing the developer, and storage means for storing information;
The storage means stores a storage area for storing information related to an integrated value of developer consumption during image formation calculated based on the print ratio;
A storage area for storing information relating to a threshold for controlling the operation of the replenishing means;
A storage area for storing information for correcting the threshold;
A cartridge characterized by comprising: A storage device mounted on a cartridge used in an image forming apparatus having a replenishing means for replenishing a developer and a means for measuring a printing ratio during image formation,
A storage area for storing information relating to an integrated value of developer consumption during image formation calculated based on the print ratio;
A storage area for storing information relating to a threshold for controlling the operation of the replenishing means;
A storage area for storing information for correcting the threshold;
A storage device comprising:

Images