JP2015152688A - image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize agitation of developer before printing.SOLUTION: An image forming apparatus acquires information on the amount of developer to be used for printing on a recording material P, from image information (S704), determines agitation time for driving an agitation section 6, from the acquired information (S705), and drives the agitation section 6 for the determined agitation time before printing on the recording material P (S708).

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer having a function of forming an image on a recording material such as a sheet.

2. Description of the Related Art Conventionally, an image forming apparatus employs a system in which a developing unit that accommodates toner (developer) is made into a cartridge and the cartridge can be attached to and detached from the image forming apparatus body. According to this method, the user can perform maintenance of the image forming apparatus without depending on the service person, so that convenience can be improved. However, in this method, if the cartridge is not used for a long period of time and kept in a certain posture, the toner stored in the storage unit is biased to one side (partially) and so-called a tapping phenomenon. May occur. When printing (image formation) is performed by a cartridge in which tapping has occurred, there is a possibility that the toner supply amount will not be stable, and the image density will become uneven.
In order to eliminate such a tapping state, Patent Document 1 discloses a method in which a stirring operation for stirring the toner is performed for a certain period of time before printing is started.

Japanese Patent Laid-Open No. 11-184200

However, in the method as disclosed in Patent Document 1, the stirring time that enables printing to a certain density is set, and the stirring operation is executed during the stirring time (a fixed time). There is a concern that a stirring operation may occur.
The present invention has been made in view of the above-described circumstances, and an object thereof is to suppress the developer agitation operation before printing to the minimum necessary.

In order to achieve the above object, the present invention provides:
An image carrier on which a latent image is formed based on image information;
A developer container that stores a developer for developing the latent image on the image carrier into a developer image;
A stirring means for stirring the developer in the developer container;
With
In the image forming apparatus for transferring the developer image on the image carrier to a recording material and printing on the recording material,
From the image information, developer amount acquisition means for acquiring information on the amount of developer used for printing on the recording material,
An agitation time determining means for determining an agitation time for driving the agitation means based on the information on the developer amount;
Control means for driving the stirring means during the stirring time determined by the stirring time determination means before printing on the recording material;
It is characterized by providing.

  According to the present invention, it is possible to minimize the developer agitation operation before printing.

Sectional drawing which shows schematic structure of the image forming apparatus of Example 1. FIG. 1 is a block diagram illustrating an example of a system configuration of an image forming apparatus according to a first embodiment. Schematic diagram showing an enlarged main section of the process cartridge of FIG. The figure which shows the flowchart of the image data process of Example 1. FIG. The figure showing the relationship between the image density information of Example 1 and stirring time The figure shown about the stirring time by the printing of Example 1 The flowchart for demonstrating until the stirring time of Example 1 is determined. The figure for demonstrating the calculation method which calculates the stirring time of Example 1. The flowchart for demonstrating until the stirring time of Example 2 is determined. The figure for demonstrating the calculation method which calculates the stirring time of Example 2. The figure for demonstrating the calculation method which calculates the stirring time of Example 3.

  DETAILED DESCRIPTION Exemplary embodiments for carrying out the present invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. It is not intended to limit the scope to the following embodiments.

[Example 1]
Example 1 will be described below.
FIG. 1 is a cross-sectional view illustrating a schematic configuration of the image forming apparatus according to the present exemplary embodiment. In this embodiment, a laser printer is applied as the image forming apparatus.
First, a schematic configuration of the entire laser printer of this embodiment will be described. In this embodiment, the yellow (Y) toner image forming unit is the first station, the magenta (M) toner image forming unit is the second station, and the cyan (C) toner image forming unit is the third station. The black (K) toner image forming unit is the fourth station.

  In the first station, a photosensitive drum 1a as an image carrier is formed by laminating a plurality of functional organic materials including a carrier generation layer that generates a charge upon exposure on a metal cylinder, a charge transport layer that transports the generated charge, and the like. The outermost layer has low electrical conductivity and is almost insulative. In this embodiment, the photosensitive drum 1a is formed by applying an organic photoconductive layer (OPC) to the outer peripheral surface of an aluminum cylinder. Both ends of the photosensitive drum 1a are rotatably supported by flanges, and a driving force is transmitted to one end from a driving motor (not shown), so that the photosensitive drum 1a is rotated counterclockwise in FIG.

The charging roller 2a as a charging unit is a conductive roller and is disposed so as to contact the surface of the photosensitive drum 1a. The surface of the photosensitive drum 1 is uniformly (uniformly) while being driven to rotate as the photosensitive drum 1a rotates. ) It is charged. A DC voltage or a voltage (charging bias voltage) obtained by superimposing an AC voltage on the DC voltage is applied to the charging roller 2a, and a small air gap upstream and downstream from the contact nip portion between the surface of the charging roller 2a and the photosensitive drum 1a. When the discharge is generated, the photosensitive drum 1a is charged.
The exposure unit 11a is composed of a scanner unit or an LED array that scans laser light with a polygon mirror, and a scanning beam 12a modulated based on an image signal is applied onto the uniformly charged photosensitive drum 1a. Irradiate. As a result, a latent image (electrostatic latent image) based on the image information is formed on the photosensitive drum 1a (on the image carrier).

The developing unit 8a as a developer container includes a developing roller 4a as a developer carrier, a toner 5a as a non-magnetic one-component developer, a stirring unit 6a, and a developer application blade 7a as a developer regulating member. It has been. The developing roller 4a is disposed so as to be adjacent to the surface of the photosensitive drum 1a, and is driven to rotate by a driving unit (not shown). Then, a developing bias voltage is applied to the developing roller 4a by a developing bias power source (not shown), whereby the latent image formed on the photosensitive drum 1a is developed into a toner image (developer image) with yellow toner. In the agitator 6a, the toner 5a accommodated in the developing unit 8a (in the developer accommodating portion) is agitated. The cleaning unit 3a cleans the transfer residual toner remaining on the photosensitive drum 1a.
The constituent members denoted by reference numerals 1a to 8a described above are integrally formed into a cartridge, and constitute an integrated process cartridge 9a that is detachable from the main body of the image forming apparatus.

Here, the intermediate transfer member 80 is supported by two rollers (secondary transfer counter roller 86 and drive roller 14) as stretch members so that an appropriate tension is maintained. By driving the driving roller 14, the intermediate transfer member 80 moves in the forward direction at substantially the same speed with respect to the photosensitive drum 1a.
Further, the intermediate transfer member 80 rotates in the arrow direction shown in FIG. 1, and the primary transfer roller 81a is disposed on the opposite side of the photosensitive drum 1a with the intermediate transfer member 80 interposed therebetween. In other words, a primary transfer roller 81a that is in contact with the intermediate transfer member 80 is provided inside the intermediate transfer member 80 so as to face the photosensitive drum 1a.
Further, a static elimination member 23a is disposed on the downstream side of the primary transfer roller 81a in the rotation direction of the intermediate transfer member 80. The drive roller 14, the charge removal member 23a, and the secondary transfer counter roller 86 are electrically grounded.

The charging roller 2a is connected to a charging bias power source 20a that is a voltage supply means to the charging roller 2a. The developing roller 4a is connected to a developing bias power source 21a that is a voltage supply unit to the developing roller 4a. Each of the primary transfer rollers 81a is connected to a primary transfer bias power source 84a that is a voltage supply means to the primary transfer roller 81a.
Although the configuration of the first station has been described above, the second, third, and fourth stations have the same configuration as the first station, and the subscripts attached to the reference numerals of the constituent members are the second, third, and so on. In the fourth station, b, c and d are set. In the following description, if no distinction is required, the subscripts a, b, c, and d given to the reference numerals are omitted to indicate that they are elements provided for any station, Explained.

  During image formation (printing and printing), the cassette pickup roller 17 is driven to raise the main unit cassette bottom plate 29 and push up the recording material P installed in the main unit cassette 16. The uppermost sheet of the recording material P pushed up or the uppermost sheet of the recording material set in the (manual feed) feeding unit 30 abuts on the cassette pickup roller 17, and the cassette pickup roller 17 rotates. Thus, it is separated from other recording materials and fed. Thus, the recording material P is separated and fed one by one, and is conveyed by the registration roller 18 to a secondary transfer portion (secondary transfer position) that is a contact portion between the secondary transfer roller 82 and the intermediate transfer body 80. The

The intermediate transfer member 80 circulates by driving the driving roller 14 so as to electrostatically attract toner to the outer peripheral surface facing the photosensitive drums 1a to 1d. When voltages are supplied from the primary transfer bias power sources 84a to 84d to the primary transfer rollers 81a to 81d, the negative color toner images on the photosensitive drums 1a to 1d are transferred to the intermediate transfer member 80 in contact with the photosensitive drums 1a to 1d. Are sequentially transferred (primary transfer) to form a multicolor image.
As a result, a multicolor image is formed on the outer peripheral surface of the intermediate transfer member 80, and the multicolor image formed on the intermediate transfer member 80 is a secondary portion that is a contact portion between the secondary transfer roller 82 and the intermediate transfer member 80. It is transported to the transfer section and transferred (secondary transfer) onto the recording material P transported to the secondary transfer section.
When the recording material P is conveyed, a voltage is applied to the secondary transfer roller 82, whereby an electric field is formed on the opposing secondary transfer opposing roller 86, and the intermediate transfer body 80 and the recording material P are separated. Dielectric polarization is generated in both layers, and electrostatic attracting force is generated between the two.

The fixing means 19 applies heat and pressure to the toner image formed on the recording material P to fix the toner image on the recording material P, and has a fixing belt (not shown) and an elastic pressure roller (not shown). ing. The elastic pressure roller sandwiches the fixing belt and forms a fixing nip portion with a predetermined width with a predetermined pressure contact force with a belt guide member (not shown). In a state where the fixing nip portion rises to a predetermined temperature and is temperature-controlled, the recording material P on which the unfixed toner image conveyed from the secondary transfer portion is formed has a fixing belt, an elastic pressure roller, and a fixing nip portion. In the meantime, it is introduced so that the image surface faces upward, that is, faces the fixing belt surface. Then, the recording material P is nipped and conveyed along the fixing nip portion together with the fixing belt with the image surface closely contacting the outer surface of the fixing belt in the fixing nip portion.
In the process in which the recording material P is nipped and conveyed along the fixing nip portion together with the fixing belt, the fixing nip portion is heated and pressurized, whereby the unfixed toner image on the recording material P is heated and fixed. An image is formed on the material P.

  If the printing operation is continuously performed through the above-described series of image forming processes, for example, residual transfer toner is accumulated on the secondary transfer roller 82, and image adverse effects such as contamination of the back of the recording material P during printing may occur. Is concerned. Therefore, a conventional image forming apparatus periodically performs a cleaning operation based on parameters such as the number of printed sheets, image print rate information, and time.

Also, some conventional image forming apparatuses are provided with a cleaning blade (hereinafter referred to as a cleaning blade) for cleaning and removing toner remaining on the photosensitive drum. In this type of apparatus, wear of the photosensitive drum related to friction between the photosensitive drum and the cleaning blade, and wobbling / damaging of the cleaning blade may be a problem.
In order to prevent this, the following is performed in order to always deposit toner on the contact portion between the photosensitive drum and the cleaning blade. The laser is forcibly emitted to form an output patch across the width of the cleaning blade in contact with the photosensitive drum and then scraped off by the cleaning blade (hereinafter, toner discharge).

FIG. 2 is a block diagram for explaining an example of the system configuration of the image forming apparatus.
The host computer 200 transmits print data (character code, graphic data, image data, process conditions, etc.) described in a page description language such as PCL to the controller unit 201. The controller unit 201 receives print data from the host computer 200. The received print data is sequentially analyzed for each color to generate image information that is a bitmap composed of dot data necessary for forming an image with the printer (hereinafter referred to as image expansion), and to the engine control unit 202. Send sequentially. Here, as an example, a method of developing an image by the controller unit 201 has been described. However, the image development is not necessarily performed by the controller unit 201. For example, the image may be developed by the host computer 200 and the image information may be transmitted to the controller unit 201.

The engine control unit 202 forms an image based on the image information sequentially input from the controller unit 201, and thus forms a latent image on the photosensitive drum 1, forms a toner image of each color, primary transfer and secondary transfer, and fixing processing. And the like to control a series of image forming operations. The processing from the formation of the latent image to the primary transfer is performed in parallel with the above image development. An interface unit 210 connects the engine control unit 202 and the controller unit 201. The interface unit 210 includes a serial communication unit 203 and an image forming signal communication unit 204. The serial communication unit 203 receives a command or signal transmitted from the controller unit 201 to the engine control unit 202, and sends a signal requesting the status of the image forming apparatus or image information from the engine control unit 202 to the controller unit 201. Send. The image forming signal communication unit 204 receives image information and the like transmitted from the controller unit 201 to the engine control unit 202. Here, the controller unit 201 or the interface unit 210 corresponds to a receiving unit that receives a print request (print reservation) including image information.

211 controls each control unit and communication unit in the engine control unit 202, and compares data sent to the controller unit 201 with data held in a ROM (not shown) of the engine control unit. CPU.
The CPU 211 drives and controls the sensor control unit 218 that controls the optical sensors 218a and 218c that detect the HP mark 218b and the toner image 218d on the intermediate transfer member 80, the intermediate transfer member 80, the photosensitive drum 1, the stirring unit 6, and the like. The drive control unit 217 is controlled.
Further, the CPU 211 has a vertical synchronization signal (/ TOP signal) 22 for starting a printing operation.
0 generation and horizontal synchronization signal (/ BD synchronization signal) 22 output from the scanner control unit 205
1 is controlled. Further, the CPU 211 includes an image formation control unit 212, a fixing control unit 213, a feeding control unit 214, a high voltage control unit 215, and a nonvolatile memory control unit 216 that perform control related to a printing operation such as a scanner motor and laser output. Control.

FIG. 3 is a schematic view showing an enlarged main sectional view of the process cartridge 9a of FIG. In FIG. 3, the developing unit 8a for stirring the toner will be described.
As described above, the developing unit 8a agitates the developing roller 4a that contacts the photosensitive drum 1a and rotates in the direction of the arrow in the drawing, the developer applying blade 7a, and the toner 5a that is contained in the developing roller 4a. It is comprised from the stirring part 6a for conveying.
Here, the stirring unit 6a is a plate-like stirring member in the present embodiment, but may have other shapes and means such as a screw shape and a roller shape as long as the developer can be stirred. Moreover, it is good also as a stirring part combining those two or more.

FIG. 4 is a diagram showing a flowchart of image data processing.
From the host computer 200, commands such as the recording material size and operation mode are sent to the controller unit 201 together with image data as image information (S10). When the image data relates to a color image, it is in the format of color information using RGB (red, green, blue) data, and each color information is assigned to device RGB data that can be reproduced by this device and converted. (S11). Subsequently, the color information of the image data is converted from device RGB data to device YMCK (yellow, magenta, cyan, black) data (S12).

This YMCK data is defined to represent the ratio to the toner amount (developer amount) obtained on the recording material when the lasers of all stations are turned on, and has a width of 0% to 100%. A data value of 0% is when the laser is completely turned off and the toner amount is zero.
Here, with respect to YMCK data, the exposure amount for each color of YMCK is calculated (derived) using a gradation table showing the relationship between the exposure amount for each color and the toner amount actually used. At that time, image density information (sometimes simply referred to as density information) d is also calculated (S13). For example, when the image data in a certain pixel (pixel) is Y = 50%, M = 70%, C = 20%, and K = 0%, the image density information d is 140% (= 50 + 70 + 20 + 0). .
Thereafter, the exposure amount of each color is converted into an actually used exposure pattern for each pixel (S14), resulting in an exposure output (S15).

In this embodiment, the image density information d is the maximum density among the pixels in one page of the recording material, and the image density information of the image data (first sheet) that is most recently exposed and output is d _1. Is stored in a RAM as a storage means. Further, the image density information d ₂ of the next image data to be exposed output (second _sheet), then the image density information of the image data to be exposed output (n-th) set to d _n, from d ₁ d _n The image density information up to is stored. Note that the detection time of the image density information d may vary depending on the size of the image data and the processing speed of the controller unit 201. Therefore, the number of image density information d stored in the RAM is not always constant. .

  In this embodiment, the image density information d is set to the maximum density among the pixels in one page of the recording material, but the range in which the maximum density is set (determined) can be printed, for example, in one page of the recording material. The entire region or a specific area (region) may be used. Further, the image density information d may be set using an average exposure amount instead of the maximum density. In this embodiment, the image density information d is used as the developer usage amount used for printing on the recording material P.

FIG. 5 shows the relationship between the image density information d and the stirring time (time for driving (operating) the stirring unit 6) tm necessary for normal (good) printing on one recording material. FIG. Since the relationship between the image density information d and the required stirring time tm varies depending on the characteristics of the toner, the structure of the stirring unit 6, the stirring method, and the usage environment, FIG. 5 shows an example thereof. The relationship shown in FIG. 5 may be stored in the RAM in advance.
Even if the image density information d approaches 0, the stirring time does not approach 0. This is because even when the image density information d is close to 0, the minimum agitation for using the cartridge is necessary. Thereafter, as d increases, more stirring time is required. This is because the higher the density is, the more toner 5a is required, and therefore the agitation unit 6 needs to be driven more and more toner 5a needs to be fed into the developing roller 4a.

  FIG. 6 is a diagram showing the agitation time by printing (stirring time during printing) tp. The agitation time tp by printing is the agitation time that is performed by driving the agitation unit 6 while a single sheet printing operation is performed. In FIG. 6, only the recording material size used in the present embodiment is described, but the stirring time tp is determined in accordance with all the recording material sizes that can be used in the image forming apparatus and recording materials outside the fixed form. There is a need. In this embodiment, the printing stirring time tp is determined (predictable) according to the recording material size obtained from the image information. However, it is determined using the actual recording material length, printing mode, and the like. May be. Further, the stirring time tp varies depending on the characteristics of the toner, the structure of the stirring unit 6, the stirring method, and the use environment. FIG. 6 shows an example of the stirring time tp. The relationship shown in FIG. 6 may be stored in the RAM in advance.

Hereinafter, a method of deriving the stirring time T when printing is requested for n recording materials will be described with reference to the flowchart of FIG. 7 and the values shown in FIG.
In the conventional image forming apparatus, the stirring time is set so that normal printing can be performed from the first sheet without using image density information.
In contrast, in this embodiment, when printing is requested for n recording materials, image density information is obtained (acquired) from the image information included in the printing request, and the stirring time is obtained from the image density information. Is set.
At this time, assuming that there is a case where further printing is performed subsequent to the printing (printing for n sheets), the stirring time is set so that the subsequent printing on the recording material after the (n + 1) th sheet can be normally performed. is there.
Here, in this embodiment, the image density information for the (n + 1) th recording material is set to the image density information that has been set so that printing can be normally performed from the first sheet. 150%.

FIG. 7 shows n + 1 sheets from the image density information d _{1 to} dn for the _n recording materials requested to be printed and the image density information dn _{+ 1} that enables printing on the ( _{n + 1} ) _th recording material. It is a flowchart for demonstrating until the stirring time T required in order to perform printing normally on a recording material is determined. Here, image density information dn _{+ 1} that enables printing on the ( _{n + 1} ) _th recording material.
Means the following image density information. That is, an image that enables printing when it is assumed that printing is performed on one (n + 1) th recording material after the printing operation for n recording materials (for which printing is requested) is completed. Concentration information. Here, printing operations are performed on n recording materials in the order in which the print requests are received.
As described above, in this embodiment, it is assumed that further printing is performed after the printing operation for the n recording materials requested for printing is completed, and normal printing is performed even when such further printing is performed. The stirring time is obtained so that
FIG. 8 is a diagram for explaining a calculation method for calculating the stirring time necessary for normal printing from the image density information in this embodiment.
Here, a method for obtaining the agitation time T necessary for normal printing when printing is requested for three recording materials will be described.
In this embodiment, the stirring time T is set to the image density information d _{1 to} d ₃ for the three (a plurality of) recording materials for which printing is requested (printing is scheduled to start from now on), and 4 for the n + 1th sheet. seeking by using the image density data d ₄ for sheet of the recording material. Here, the image density information d4 for the _fourth recording material is 150% as described above.
As a result, the three recording materials requested to be printed can be printed normally while shortening the stirring time, and the fourth and subsequent prints were performed following the print request. However, it is intended to enable normal printing. Here, in this embodiment, the amount of stirring in the stirring unit 6 is expressed by time, but may be expressed by the number of rotations and the amount of rotation of the stirring unit 6.
The flowchart of the present embodiment is executed by the CPU 211 that controls each control of the engine control unit 202, and is started when it is determined that the stirring operation is necessary and the initialization operation of the printer body including the stirring operation is started. To do.

In S701, it is determined whether the stirring operation has been completed. If it has been completed, this flowchart ends. If not completed, the process proceeds to S702.
In step S702, it is determined whether the controller unit 201 has received a print command. If a print command has been received, the process proceeds to S703 to determine the agitation time. If not received, the process returns to S701. In this embodiment, a case where the information on the first to third sheets is received as a print command will be described.
In S703, the stored stirring execution time tf is acquired. The storage of the stirring execution time tf will be described in S708 and 709. Here, tf is set to 0.

In S704, acquires the n Like the image density data _d 1 to d _n of going to start from now, the image density information _{d n + 1} that allows the printing of one of the following (n + 1 th).
First, image density information d _{1 to} d ₃ of each recording material is acquired from the controller unit 201. Here, as shown in FIG. 8, the image density information d _{1 to} d ₃ is d ₁ = 50, d ₂ = 100, and d ₃ = 100, respectively. Next, the density of the fourth sheet is image density information d ₄ that enables printing of the next sheet (n + 1 sheet), and is preset to 150% in this embodiment, and d ₄ = 150. It becomes. Here, the CPU 211 that executes S704 corresponds to a developer amount acquisition unit.

In S705, based on the image density information _d 1 to d _n determined in S704, determines a stirring time _{td 1 ~td n +} 1. Here, the CPU 211 that executes S705 corresponds to a stirring time determination unit.
From the relationship of FIG. 5, the stirring times td _{1 to} td ₄ necessary for normal printing on each recording material are acquired. When the stirring times td _{1 to} td ₄ corresponding to (obtained from) d ₁ = 50, d ₂ = 100, d ₃ = 100, d ₄ = 150 shown in FIG. 8 are obtained from FIG. 5, respectively, td ₁ = 60 , Td ₂ = 90, td ₃ = 90, and td ₄ = 100. In the present embodiment, is 4 th image density information d ₄ is set in advance of, it was determined stirring time td ₄ from the image density information, 4th stirring time td ₄ is set in advance Also good. The agitation time td ₄ for the fourth sheet (n + 1 sheet) is set in advance to be equal to the agitation time when the agitation unit 6 is driven in a state where no print request has been received.

In S706, stirring times tp _{1 to} tp _n by printing are acquired. Based on the recording material size information acquired from the controller unit 201, the stirring times tp _{1 to} tp ₃ by printing are acquired from FIG. Here, as shown in FIGS. 6 and 8, tp ₁ = 10, tp ₂ = 20, and tp ₃ = 25. Here, the CPU 211 executing S706 corresponds to an agitation time predicting unit that predicts the time during which the agitation unit 6 is driven during the printing operation on the recording material from the image information included in the print request.

In S707, first, stirring times tm _{1 to} tmn _{n + 1} corresponding to the respective recording materials are acquired.
n + 1 sheet a sheet of stirring time tm _a corresponding to the recording material (predetermined sheet) is stirred from time td _a obtained in S705, in the printing operation from the first sheet to a-1 th Is determined by subtracting the stirring time Σtp _a-1 which is the sum of the times (total time) during which the stirring operation is performed. The formula for determining tm is shown below.
tm _a = td _a −Σtp _a−1 Equation 1
(However, tp ₀ = 0, a ≦ n + 1)
At this time, if the 0,0 or more if the value obtained from Equation 1 is less than 0, and its value as tm _a. The stirring time tm determined corresponding to each recording material is stored in the RAM. Here, the CPU 211 that executes control for determining tm in step S707 corresponds to a correction unit.

Here, it is necessary to secure a stirring time necessary for normal printing on all (n + 1) recording materials. Accordingly, in S707, the maximum maximum stirring time (maximum value Tm) among the stirring times tm corresponding to the respective recording materials stored in the RAM is necessary for normal printing on all the recording materials. Selected as agitation time.
Furthermore, the stirring time T is obtained by subtracting the acquired current stirring execution time tf from the maximum value Tm. The formula for determining T is shown below.
T = Tm−tf Equation 2
By using the above equation 1 for the above td and tp (FIG. 8), tm ₁ = 60, tm ₂ = 80, tm ₃ = 60, tm ₄ = 45 are obtained, and Tm is 80. Here, since tf = 0, the stirring time T is 80 seconds from the above equation 2.

In S708, the driving of the stirring unit 6 is started (before printing on the recording material P), and the stirring operation is started. And the measurement of the elapsed time from the start of stirring operation is started. In S709, it is determined from the measured time and the stirring time T whether the stirring is completed. When the elapsed time from the start of measurement (stirring execution time) is equal to the stirring time T, the time measurement from the start of the stirring operation is terminated and stored in the RAM, and this flowchart is terminated. If not completed, the process proceeds to S710.
In S710, it is confirmed whether or not the controller unit 201 has received a print command. If the print command has been received, the time measurement from the start of the stirring operation is terminated and stored in the RAM, and the process proceeds to S703. Again, the stirring time T is determined.

Conventionally, the stirring time has been set so that printing of a predetermined image density set in advance can be normally performed from the first sheet. In this embodiment, the stirring time is the (n + 1) th stirring time (stirring time when the stirring unit 6 is driven in a state in which no printing request is received), and printing of n sheets requested for printing is performed. For the printing on the material, the stirring time was determined based on the image density information.
Thus, after completion of the printing operation for the n recording materials requested to be printed, even if printing is performed on one or more recording materials, the toner is sufficiently stirred, Printing can be performed satisfactorily without causing unevenness in density. Therefore, a high quality image can be obtained.
In this embodiment, since the (n + 1) -th image density information is 150% as shown in FIG. 8, if the stirring time is set as usual, the stirring time is 100 seconds from FIG. On the other hand, in this embodiment, as described above, the stirring time T is 80 seconds.
Thus, in this embodiment, the respective image density information d ₁ to d _n of n pieces of scheduled to begin printing now, the image density information d _{n + 1} that allows the printing of the (n + 1) th, the stirring time required By determining the value, the stirring time can be shortened, and the stirring time can be minimized.
As a result, it is possible to suppress a decrease in productivity that occurs when the toner is agitated.

[Example 2]
Example 2 will be described below.
In the present embodiment, it is characterized in that from each image density information d ₁ to d _n of n pieces of scheduled to begin printing now, to determine the stirring time T. Here, in Example 1, the stirring time tp by printing is taken into consideration for determining the stirring time T. However, assuming the configuration of the printer main body and the stirring unit 6 in which stirring is not performed by printing, In the embodiment, a method that does not take into account the stirring time tp by printing will be described. In the present embodiment, the image density information dn _{+ 1} that enables printing on the ( _{n + 1} ) _th recording material, which is taken into consideration in the first embodiment, is not taken into consideration. In the present embodiment, the different components from the first embodiment will be described, and the description of the same components as those in the first embodiment will be omitted.

FIG. 9 illustrates the process up to the determination of the stirring time T necessary for normal printing from the n pieces of image density information d scheduled to start from the controller unit 201 that receives the print request. It is a flowchart for doing. FIG. 10 is a diagram for explaining a calculation method for calculating the agitation time necessary for normal printing from the image density information used in this embodiment.
In this embodiment, as shown in FIG. 10, a method of calculating the stirring time T necessary for normal printing on the three recording materials based on the _three image density information d _{1 to} d _3. Will be explained.

Hereinafter, a method of calculating the stirring time T will be described using the flowchart of FIG. 9 and the values shown in FIG.
This flowchart is executed by the CPU 211 that controls each control of the engine control unit 202, and is started when it is determined that the stirring operation is necessary and the initialization operation of the printer body including the stirring operation is started.

S901 to S903 are the same as S701 to S703 described in the first embodiment. In S903, tf is set to 0 also in the present embodiment.
In S904, it acquires the image density information _d 1 to d _n of the recording material from the print command. The image density information d is assumed to be d ₁ = 50, d ₂ = 100, and d ₃ = 100 from FIG.
In S905, based on the image density information d ₁ to d ₃ determined in S904, it acquires the stirring time td needed for a successful printing on the recording medium from the relationship of FIG. When the stirring times td corresponding to d ₁ = 50, d ₂ = 100, and d ₃ = 100 shown in FIG. 10 are obtained from FIG. 5, respectively, td ₁ = 60, td ₂ = 90, and td ₃ = 90.

In S906, first, the stirring time tm corresponding to each recording material is acquired.
Here, it is necessary to ensure the stirring time necessary for normal printing on all (n sheets) recording materials. Therefore, the maximum value Tm among the stirring times tm corresponding to the respective recording materials is the stirring time necessary for normal printing on all the recording materials. Then, as in Example 1, the agitation time T is obtained by subtracting the acquired current agitation execution time tf from the maximum value Tm as shown in Equation 2.
Here, since Tm = 90 and tf = 0, the stirring time T is 90 seconds.
S907 to S909 are the same as S708 to S710 described in the first embodiment.

Conventionally, the stirring time has been set so that printing of a predetermined image density set in advance can be normally performed from the first sheet. Here, if the predetermined image density is 300%, the conventional stirring time is 150 seconds from FIG. On the other hand, in this embodiment, as described above, the stirring time T is 90 seconds.
Thus, also in the present embodiment, the same effect as in the first embodiment can be obtained.

[Example 3]
Example 3 will be described below.
In the present embodiment, a method will be described in which the controller unit 201 determines the stirring time T when a new print command is received during execution of the stirring operation of the first embodiment. That is, a method for determining the stirring time T again when it is determined in S710 of the flowchart of FIG. 7 described in the first embodiment that a new print command has been received will be described. In the present embodiment, the different components from the first embodiment will be described, and the description of the same components as those in the first embodiment will be omitted.

FIG. 11 is a diagram for explaining a calculation method for calculating the stirring time necessary for normal printing from image information in the present embodiment.
In this embodiment, the image density information d ₁ to d 3 of three scheduled to begin printing _now, the recording material size is the same as in Example 1, each value of up to 3rd is paper passing projected number 11 Is the same as FIG.

Hereinafter, a method of determining the stirring time T when a new print command is received during execution of the stirring operation will be described using the flowchart of FIG. 7 and the values shown in FIG.
Steps S701 to S707 are the same as those in the first embodiment. Then, in S707, the stirring time T is calculated as 80 seconds, the process proceeds to S708, and the stirring operation is started. In S709, the current stirring execution time tf is set to the timing of 10 seconds, and the process proceeds to S710.

In step S710, it is assumed that the controller unit 201 has received a new print command (fourth sheet), and the process advances from step S710 to step S703. In S703, the current stirring execution time tf becomes 10, and the process proceeds to S704. At this time, the stirring operation is temporarily stopped.
In S704, it acquires the image density information _d 1 to d ₄ of the recording medium from the print command. As shown in FIG. 11, the image density information d _{1 to} d ₄ is d ₁ = 50, d ₂ = 100, d ₃ = 100, and d ₄ = 300, respectively. The image density information of the fifth sheet in this embodiment corresponds to the image density information that enables printing on the (n + 1) th recording material described in the embodiment 1, and is 150% in this embodiment. d ₅ = 150.

In S705, based on the image density information _d 1 to d ₅ determined in S704, it acquires the stirring time _td 1 _{~td 5} necessary for a successful printing on the recording medium from the relationship of FIG. When the stirring times td _{1 to} td ₅ corresponding to d ₁ = 50, d ₂ = 100, d ₃ = 100, d ₄ = 300, and d ₅ = 150 shown in FIG. 11 are obtained from FIG. 5, td ₁ = 60, respectively. , Td ₂ = 90, td ₃ = 90, td ₄ = 150, and td ₅ = 100.
In S706, the stirring times tp _{1 to} tp ₄ by printing are acquired. Based on the recording material size information acquired from the controller unit 201, the stirring times tp _{1 to} tp ₄ by printing are acquired from FIG. Here, as shown in FIGS. 6 and 11, tp ₁ = 10, tp ₂ = 20, tp ₃ = 25, and tp ₄ = 10.

In S707, first, by using Equation 1 shown in Example 1 for the above td ₁ to td ₅ and tp _{1 to} tp ₄ (FIG. 11), tm ₁ = 60, tm ₂ = 80, tm ₃ = 60, tm ₄ = 95, tm ₅ = 35 are obtained, and Tm is 95. In this embodiment, as described above, since tf = 10, the stirring time T is 85 seconds from the equation 2 shown in the first embodiment.

S708 to S709 are the same as those in the first embodiment, and the stirring operation is restarted in S708. If the elapsed time from the start of measurement becomes equal to the stirring time T in S709, the time measurement from the start of the stirring operation is terminated and the RAM is started. And finish this flowchart. If not completed, the process proceeds to S710.
In S710, it is confirmed whether or not the controller unit 201 has received a print command. If the print command has been received, the time measurement from the start of the stirring operation is terminated and stored in the RAM, and the process proceeds to S703. The stirring time T is determined again by the procedure.

Conventionally, the stirring time has been set so that printing of a predetermined image density set in advance can be normally performed from the first sheet. In this embodiment, this agitation time is the (n + 1) th agitation time, and the printing time for the n recording materials requested to be printed is determined based on the image density information. In this embodiment, since the (n + 1) -th image density information is 150% as shown in FIG. 11, if the stirring time is set as usual, the stirring time is 100 seconds from FIG. On the other hand, in this embodiment, as described above, the stirring time T is 95 seconds.
Thus, also in the present embodiment, the same effects as those of the first embodiment can be obtained.

  DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum, 8 ... Developing unit, 6 ... Stirring part, 202 ... Engine control part, 211 ... CPU, P ... Recording material

Claims (11)

An image carrier on which a latent image is formed based on image information;
A developer container that stores a developer for developing the latent image on the image carrier into a developer image;
A stirring means for stirring the developer in the developer container;
With
In the image forming apparatus for transferring the developer image on the image carrier to a recording material and printing on the recording material,
From the image information, developer amount acquisition means for acquiring information on the amount of developer used for printing on the recording material,
An agitation time determining means for determining an agitation time for driving the agitation means based on the information on the developer amount;
Control means for driving the stirring means during the stirring time determined by the stirring time determination means before printing on the recording material;
An image forming apparatus comprising:   When printing is performed on a plurality of recording materials, the control means drives the stirring means during the maximum maximum stirring time among stirring times determined for each recording material. The image forming apparatus according to claim 1. The agitation time during printing in which the agitation means is driven while printing on the recording material can be predicted based on image information,
The first stirring time, which is the stirring time corresponding to the predetermined recording material among the plurality of recording materials,
Information on the developer amount;
Among the plurality of recording materials, a total time that is the sum of the stirring time during printing predicted for the recording material on which printing is performed before the predetermined recording material, and
The image forming apparatus according to claim 2, wherein the image forming apparatus is determined based on   The first stirring time is a time obtained by subtracting the total time from a second stirring time which is a stirring time determined by the stirring time determination means based on the developer amount information. The image forming apparatus according to claim 3. Receiving means for receiving a print request including image information;
When the receiving means has received a print request for a plurality of recording materials,
Storage means for storing the stirring time determined corresponding to each recording material from the image information included in the received print request,
With
The control means includes
2. The image according to claim 1, wherein the largest maximum stirring time is selected from among the plurality of stirring times stored in the storage means, and the stirring means is driven during the maximum stirring time. Forming equipment. Receiving means for receiving a print request including image information;
Storage means for storing the stirring time determined from the image information included in the received print request;
With
In the storage means,
After completion of the printing operation for the recording material for which printing is requested, the stirring time corresponding to the recording material is stored in advance when it is assumed that printing is further performed on one recording material,
The said control means selects the largest maximum stirring time among the several stirring time memorize | stored in the said memory | storage means, The said stirring means is driven during this maximum stirring time, It is characterized by the above-mentioned. The image forming apparatus according to 5. When the receiving means has received a print request for a plurality of recording materials,
The image forming apparatus according to claim 6, wherein the storage unit stores a stirring time determined corresponding to each recording material from image information included in the received print request. The stirring time stored in advance in the storage means is
The image forming apparatus according to claim 6, wherein the image forming apparatus is equal to a stirring time when the stirring unit is driven in a state where the receiving unit has not received a print request. Agitation time prediction means for predicting a time during which the agitation means is driven while printing on a recording material from image information included in the print request received by the reception means;
The receiving means sequentially receives print requests for a plurality of recording materials,
When a printing operation is performed on a recording material corresponding to the printing request in the order in which the receiving unit receives the printing request,
A value obtained by subtracting the sum of each time predicted by the stirring time predicting unit for the recording materials up to the (a-1) th recording material from the stirring time determined for the ath recording material among a plurality of sheets. Correction means for setting the agitation time corresponding to the a-th recording material;
The image forming apparatus according to claim 5, further comprising: The control means includes
When the receiving unit receives a new print request while driving the stirring unit, the driving of the stirring unit is temporarily stopped and the stirring unit is driven until the printing request is received. The agitation execution time that has been stored is stored in the storage means, and again the maximum agitation time for all print requests including the new print request is determined,
After that, restart the drive of the stirring means,
10. The image forming apparatus according to claim 5, wherein the agitation unit is driven during a time obtained by subtracting the agitation execution time from the determined maximum agitation time.   11. The developer amount acquisition unit according to claim 1, wherein the developer amount acquisition unit determines the developer amount from image information in the entire printable area of the recording material or in a specific area of the image information. The image forming apparatus according to claim 1.

Images