JP2007264510A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of preventing an image defect associated with the deterioration of developer. <P>SOLUTION: The image forming apparatus is equipped with: an image information signal integrating means to integrate an image information signal; a developer carrier revolving speed integrating means 10 to calculate and integrate the revolving speed of a developer carrier; a developer forcibly consuming means to forcibly consume developer without outputting it as an image; and a control means 9 to control the developer forcibly consuming means based on an integrated value from the developer carrier revolving speed integrating means 10 and an integrated value from the image information signal integrating means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In the present invention, an electrostatic latent image corresponding to an image information signal is formed on an image carrier by, for example, electrophotography or electrostatic recording, and the electrostatic latent image is converted into a visible image by a developing device. The present invention relates to an image forming apparatus such as a copying machine or a printer.

  FIG. 8 shows an example of a conventional image forming apparatus. In this example, the electrophotographic image forming apparatus 100 has a drum-shaped electrophotographic photosensitive member (hereinafter referred to as “photosensitive drum”) 1 that is an image bearing member in a freely rotatable manner. The photosensitive drum 1 is uniformly charged by a charging device 2 and then an information signal is exposed by an exposure device 3 such as a laser beam scanner to form an electrostatic latent image. The developing device 4 is a developing unit. Visualize. Next, the visible image is transferred by the transfer device 5 to the transfer material P that is a recording medium conveyed by a transfer material conveying means (not shown), and further fixed by the fixing device 6 to form a permanent image. obtain. Further, the transfer residual toner on the photosensitive drum 1 is removed by the cleaning device 7.

  Next, the developing device 4 will be described.

  The developing device 4 includes a developing container 4a and a nonmagnetic developing sleeve 4b as a developer carrying member. The developing sleeve 4b is rotatably arranged in the developing container 4a with a part of the outer peripheral surface thereof exposed to the outside of the developing device 4, and the developing roller 4b is fixed in a non-rotating manner and has a magnet roller 4c. It is inserted. A developer coating blade 4d is provided opposite to the developing sleeve 4b. The developing container 4a contains a two-component developer 4e, and a developer stirring member 4f is cast on the bottom side in the developing container 4a. Further, replenishing toner is accommodated in the toner replenishing tank 4g.

  The two-component developer (developer) 4e in the developing container 4a is mainly a mixture of a non-magnetic toner and a magnetic carrier, and is stirred by the developer stirring member 4f. In the developing container 4a, a two-component developer is rubbed to give a predetermined charge to the toner.

  The toner is particles such as polyester or styrene acrylic in which a pigment is dispersed, and is given an electric charge by rubbing against a carrier in which a magnetic material such as ferrite is coated with acrylic or silicone resin. In order to stably develop a latent image set at a predetermined potential at a constant density, it is necessary that the charge of the toner is stable. For this purpose, the developer is sufficiently contained in the developing container 4a. Must be restrained and rubbed. The charge given to the toner by this rubbing is mainly determined by the charge imparting ability of the carrier and the resistance value of the developer.

  The developing sleeve 4b is disposed in close proximity to the photosensitive drum 1. A facing portion between the photosensitive drum 1 and the developing sleeve 4b is a developing portion c. The developing sleeve 4b is rotationally driven in the direction opposite to the traveling direction of the photosensitive drum 1 in the developing unit c. Due to the magnetic force of the magnet roller 4c in the developing sleeve 4b, a part of the two-component developer 4e in the developing container 4a is adsorbed and held on the outer peripheral surface of the developing sleeve 4b as a magnetic brush layer. The magnetic brush layer is rotated and conveyed with the rotation of the developing sleeve 4b, and is layered into a predetermined thin layer by the developer coating blade 4d, and comes into contact with the surface of the photosensitive drum 1 at the developing portion c to contact the surface of the photosensitive drum. Rub moderately.

  A predetermined developing bias is applied from the power source S2 to the developing sleeve 4b. The developing bias voltage for the developing sleeve 4b is an oscillating voltage obtained by superimposing a DC voltage (Vdc) and an AC voltage (Vac).

  With the above configuration, the developer 4e is coated as a thin layer on the surface of the rotating developing sleeve 4b. The toner in the developer 4e coated in a thin layer on the developing sleeve 4b selectively adheres to the surface of the photosensitive drum 1 corresponding to the electrostatic latent image by the electric field due to the developing bias, and the electrostatic latent image is formed. Developed as a toner image.

  Toner consumed during development is supplied from the toner supply tank 4g. This replenishment amount is determined by a CPU (not shown) based on a signal from a developer concentration detecting means (not shown) by optical or electromagnetic means.

  With the above-described configuration, the developing device 4 holds the developer supplied to the surface of the developing sleeve 4b by the developer stirring member 4f in a magnetic brush state by the magnetic force of the magnet roller 4c. The magnetic brush-like developer is conveyed to a portion (developing unit) c facing the photosensitive drum 1 based on the rotation of the developing sleeve 4b. The developer coating blade 4d cuts off the magnetic brush and develops the developing unit. The amount of developer conveyed to c is properly maintained.

  However, the conventional example has the following phenomenon.

  That is, the toner in the developer is consumed by being developed, replenished from the toner replenishing tank, and the toner in the developer is replaced by outputting an image. However, when images that consume a small amount of toner are continuously output, the toner is replaced little by little, and as a result, the time during which one toner exists in the developing device 4 becomes longer. For this reason, the developer coating blade 4d and its surroundings are rubbed for a long time and stirred by the developer stirring member 4f.

  Thus, the toner in the developer that has been repeatedly rubbed and stirred for a long period of time becomes irregular in shape, uneven in particle size distribution, and improves the fluidity of the developer. External additives such as titanium oxide particles added for the purpose are embedded in the toner surface. As a result, deterioration such as a decrease in the fluidity of the developer may occur, and an image having a desired image quality may not be obtained.

  In addition, the charge of the toner is usually stabilized by rubbing several times around the developer coating blade 4d and its surroundings. However, the charge is gradually given by repeating rubbing, and a predetermined charge is obtained. It may greatly exceed the amount.

  As the charge of the toner increases in this way, the amount of toner adhering to the latent image having the same potential difference with respect to the developing sleeve 4b formed on the photosensitive drum 1 decreases compared to the initial state. This appears as image quality deterioration such as a decrease in density and a decrease in graininess in the low density portion when the image is output.

Therefore, a technique described in Patent Document 1 has been proposed. That is, when an image having an image ratio lower than a predetermined value is formed, including means for determining the size of the image ratio based on the density information of the image and means for forcibly consuming the toner according to the image ratio information The toner is forcibly consumed. Thereby, it is intended to prevent deterioration of image quality such as density reduction and deterioration of graininess in a low density portion.
Japanese Patent Laid-Open No. 9-034243

  However, in the technology for forcibly consuming the toner as in the above-described conventional example, the ratio of the total area of the toner image to the surface area of the transfer material is used as the image ratio. ) Of the developing sleeve is not taken into consideration.

  Here, with reference to FIGS. 9A and 9B, problems of a conventionally used toner consumption calculation method based on an image ratio will be described.

  FIGS. 9A and 9B are image diagrams showing how images are formed between different papers within a range where the developing sleeve can form images within a certain period of time during continuous image formation. is there.

  In an actual image forming apparatus, when the image is formed on a double-sided image or a paper type such as cardboard, the interval between the sheets may be lengthened due to the temperature control of the transport mechanism and the fixing device. 9 It is conceivable that a situation such as (a) and (b) occurs.

  Here, in FIGS. 9A and 9B, for simplification, it is assumed that the image size is the same and the image ratio is 5%, and FIG. 9A and FIG. The space between the sheets is such that the ratio of the number of image formations in FIG. 9B is 3: 2.

  When an image is created under the conditions shown in FIGS. 9A and 9B, the amount of toner consumed within the same imageable range is 3: 2, and the amount shown in FIG. 9A is larger. However, in the conventional toner consumption calculation method, the image ratio is 5% in both the cases of FIGS. 9A and 9B.

  As described above, in the conventional toner consumption amount calculation method based on the image ratio, the same image ratio is obtained even though the rotation distance of the developing sleeve is the same within a certain time and the toner consumption is different. It was calculated as a percentage. That is, the longer the interval between sheets, the smaller the actual toner consumption compared to the image ratio.

  Similarly, even when the paper sizes are different, the paper interval is generally changed. The longer the paper interval, the smaller the actual toner consumption compared to the image ratio.

  Further, even in automatic control other than during image formation, there is a mode in which the developing sleeve is idled in order to optimize the charge amount of the developer. In the conventional calculation method, such idle rotation time of the developing sleeve is not taken into consideration.

  As described above, according to the conventional method, the transfer ratio can be used as the image ratio even in the image forming conditions with different paper intervals (non-image forming areas) and paper sizes, and under the environmental conditions in which the idle rotation time of the developing sleeve is automatically controlled. The ratio of the total area of the toner image to the surface area of the toner was used.

  Actually, since the developer is deteriorated even when the developing sleeve is idling, the image is produced under an image forming condition where a paper interval is long and an automatic condition in which automatic control is easily performed (or control time is likely to be long). In the case of imaging, deterioration may be accelerated.

  Accordingly, an object of the present invention is to provide an image forming apparatus capable of preventing image defects due to deterioration of a developer.

The above object is achieved by the image forming apparatus according to the present invention. In summary, the present invention
An image carrier on which an electrostatic image corresponding to the image information signal is formed;
A developer container that stores the developer, and a developer that is rotatably disposed in the developer container, carries and conveys the developer housed in the developer container, and develops an electrostatic image on the image carrier. A developing device comprising a carrier;
In an image forming apparatus having
Image information signal integrating means for integrating the image information signal;
A developer carrying member rotational speed integrating means for calculating and integrating the rotational speed of the developer carrying member;
Developer forcible consumption means for forcibly consuming the developer without outputting it as an image;
Control means for controlling the developer forcible consumption means based on the integrated value from the developer carrier rotation speed integrating means and the integrated value from the image information signal integrating means;
An image forming apparatus comprising:

  According to the present invention, since the developer can be forcibly consumed based on the integrated value of the rotation speed of the developer carrier and the integrated value of the image information signal, the deterioration of the developer can be prevented more effectively. can do.

  The image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.

Example 1
FIG. 1 shows an embodiment of an image forming apparatus according to the present invention. In this embodiment, the image forming apparatus is an electrophotographic laser beam printer.

  The image forming apparatus of this embodiment has a drum-shaped electrophotographic photosensitive member that is an image carrier, that is, a photosensitive drum 1 rotatably. The photosensitive drum 1 includes a charging device 2 as a charging unit around the photosensitive drum 1 in the rotation direction. The photosensitive drum 1 is uniformly charged by the charging device 2 and then an information signal is exposed by an exposure device 3 such as a laser beam scanner to form an electrostatic latent image. The electrostatic latent image on the photosensitive drum 1 is developed by a developing device 4 which is a developing unit containing a developer (toner), and becomes a visible image, that is, a toner image. Next, the toner image on the photosensitive drum 1 is transferred to a transfer material P as a recording medium conveyed by a transfer material conveying means (not shown) by a transfer device 5 as a transfer means. The transfer material P is fed to the fixing device 6, and the toner image on the transfer material P is fixed and becomes a permanent image. Further, the transfer residual toner on the photosensitive drum 1 is removed by the cleaning device 7.

  Next, the image forming process means will be described in more detail.

(A) Image carrier As described above, the image forming apparatus 100 includes the photosensitive drum 1 as an image carrier. In this embodiment, the photosensitive drum 1 is an organic photoconductor (OPC) having a negative charging property, and has an outer diameter of 30 mm and an arrow having a process speed (peripheral speed) of 130 mm / sec centering on the central support shaft. It is rotated counterclockwise.

(B) Charging Unit The image forming apparatus 100 includes a contact charging device (contact charger) 2 as a charging unit that uniformly charges the surface of the photosensitive drum 1. In this embodiment, the contact charging device 2 is a charging roller (roller charger), and a charging portion (charging nip portion, contact portion) using a discharge phenomenon that occurs in a minute gap between the photosensitive drum 1 and the contact charging device 2. At a, the photosensitive drum 1 is charged.

  The charging roller 2 is rotatably held at both ends of a core metal (support member) 2b by a bearing member (not shown), and is urged toward the photosensitive drum 1 by a pressing spring 2a. 1 is brought into pressure contact with a predetermined pressing force. As a result, the charging roller 2 rotates following the rotation of the photosensitive drum 1.

  A charging bias voltage of a predetermined condition is applied to the cored bar 2b of the charging roller 2 from a power source S1 controlled by the CPU 9. As a result, the surface of the rotating photosensitive drum 1 is contact-charged with a predetermined polarity and potential.

  In the present embodiment, the charging bias voltage for the charging roller 2 is an oscillating voltage in which a DC voltage (Vdc) and an AC voltage (Vac) are superimposed. More specifically, it is an oscillating voltage in which a DC voltage of −500 V, a frequency of 1.3 kHz, a peak-to-peak voltage Vpp of 1.5 kV, and a sinusoidal AC voltage are superimposed. By this charging bias voltage, the surface of the photosensitive drum 1 is uniformly contact-charged to −500 V (dark potential Vd) which is the same as the DC voltage applied to the charging roller 2.

(C) Exposure Unit The image forming apparatus 100 includes an exposure unit 3 as an exposure unit that forms an electrostatic latent image on the surface of the photosensitive drum 1 that has been charged. In this embodiment, the exposure apparatus 3 is a laser beam scanner using a semiconductor laser.

  The laser beam scanner 3 outputs a laser beam L modulated in accordance with an image signal sent from a host processing device such as an image reading device (not shown) to the image forming device side. The laser beam L scans (image exposes) the surface of the rotating photosensitive drum 1 that has been uniformly charged at the exposure position (exposure unit) b. By this laser scanning exposure, the potential of the surface of the photosensitive drum 1 irradiated with the laser light L is lowered, and electrostatic latent images corresponding to image information are sequentially formed on the surface of the rotating photosensitive drum 1. To go.

(D) Developing Unit The image forming apparatus 100 includes a developing device 4 as a developing unit that supplies a developer according to the electrostatic latent image on the photosensitive drum 1 and reversely develops the electrostatic latent image as a toner image. In the present embodiment, the developing device 4 is a developing device that employs a two-component contact developing system that performs development while bringing a magnetic brush made of a two-component developer composed of toner and carrier into contact with the photosensitive drum 1.

  The developing device 4 includes a developing container 4a and a nonmagnetic developing sleeve 4b as a developer carrying member. The developing sleeve 4b is rotatably arranged in the developing container 4a with a part of the outer peripheral surface thereof exposed to the outside of the developing device 4. In the developing sleeve 4b, a magnet roller 4c is inserted in a non-rotating manner. A developer coating blade 4d is provided opposite to the developing sleeve 4b. The developing container 4a contains a two-component developer 4e, and a developer stirring member 4f is disposed on the bottom side in the developing container 4a. A replenishment developer (toner) is accommodated in the toner replenishing tank 4g.

  The two-component developer 4e in the developing container 4a is mainly a mixture of a nonmagnetic toner and a magnetic carrier, and is stirred by the developer stirring member 4f.

In this embodiment, the resistance of the magnetic carrier is about 10 ¹³ Ω · cm, and the particle size (volume average particle size) is about 40 μm. The volume average particle diameter means a 50% median diameter measured by dividing the range of 0.5 to 350 μm into 32 logarithms using a laser diffraction particle size distribution measuring device HEROS (manufactured by JEOL Ltd.). The toner is triboelectrically charged to a negative polarity by rubbing with the magnetic carrier.

  The developing sleeve 4b is disposed in close proximity to the photosensitive drum 1 while maintaining the closest distance (S-Dgap) to the photosensitive drum 1 at 350 μm. A facing portion between the photosensitive drum 1 and the developing sleeve 4b is a developing portion c.

  The developing sleeve 4b is rotationally driven in the developing portion c at a process speed (200 mm / sec in this embodiment) approximately 1.5 times that of the photosensitive drum 1 in the direction opposite to the traveling direction of the photosensitive drum 1. Due to the magnetic force of the magnet roller 4c in the developing sleeve 4b, a part of the two-component developer 4e in the developing container 4a is adsorbed and held on the outer peripheral surface of the developing sleeve 4b as a magnetic brush layer. The magnetic brush layer is rotated and conveyed with the rotation of the developing sleeve 4b, and is layered into a predetermined thin layer by the developer coating blade 4d, and comes into contact with the surface of the photosensitive drum 1 at the developing portion c to contact the surface of the photosensitive drum. Rub moderately.

  A predetermined developing bias is applied to the developing sleeve 4b from a power source S2 controlled by the CPU 9. In this embodiment, the developing bias voltage for the developing sleeve 4b is an oscillating voltage obtained by superimposing a DC voltage (Vdc) and an AC voltage (Vac). More specifically, it is an oscillating voltage in which a DC voltage of −350 V, a frequency of 8.0 kHz, a peak-to-peak voltage of 1.8 kV, and a rectangular wave AC voltage are superimposed.

  With the above configuration, the developer 4e is coated as a thin layer on the surface of the rotating developing sleeve 4b. The toner in the developer 4e conveyed to the developing unit c is selectively attached to the surface of the photosensitive drum 1 corresponding to the electrostatic latent image by the electric field due to the developing bias, and the electrostatic latent image is developed as a toner image. The In this embodiment, toner adheres to the exposed portion of the surface of the photosensitive drum 1 and the electrostatic latent image is reversely developed to form a toner image.

(E) Transfer Unit, Fixing Unit, and Cleaning Unit The image forming apparatus 100 includes the transfer device 5 as a transfer unit. In this embodiment, the transfer device 5 is a transfer roller. The transfer roller 5 is pressed against the photosensitive drum 1 with a predetermined pressing force, and the pressure nip portion is a transfer portion d. The transfer material P is fed to the transfer portion d at a predetermined control timing by a transfer material conveying means (not shown).

  The transfer material P fed to the transfer part d is nipped and conveyed between the rotating photosensitive drum 1 and the transfer roller 5. In the meantime, a positive transfer bias having a polarity opposite to the negative polarity that is the normal charging polarity of the toner, +2 kV in this embodiment, is applied to the transfer roller 5 from the power source S3 controlled by the CPU 9. As a result, the toner image on the surface side of the photosensitive drum 1 is sequentially electrostatically transferred onto the surface of the transfer material P that is nipped and conveyed by the transfer portion d.

  The transfer material P that has received the transfer of the toner image through the transfer portion d is sequentially separated from the surface of the photosensitive drum 1 and conveyed to the fixing device 6. In this embodiment, the fixing device 6 is a heat roller fixing device, and the transfer material P is subjected to a toner image fixing process by the fixing device 6 and is output as an image formed product (print, copy).

  After the toner image is transferred to the transfer material P in the transfer portion d, the transfer residual toner remaining on the surface of the photosensitive drum 1 is removed from the surface of the photosensitive drum by the cleaning device 7.

  The configuration of the image forming apparatus is not necessarily a configuration in which the toner image is directly transferred from the photosensitive drum 1 to the transfer material P, but is transferred from the photosensitive drum to an intermediate transfer body that temporarily holds and conveys the toner image. The structure which transfers to a transfer material from a body may be sufficient.

  Here, the configuration and operation of the image forming apparatus provided with the intermediate transfer member are well known to those skilled in the art, and will be briefly described with reference to FIG.

  The image forming apparatus provided with the intermediate transfer body shown in FIG. 2 differs from the image forming apparatus shown in FIG. 1 mainly in that an intermediate transfer body 21 and a secondary transfer roller 22 as secondary transfer means are provided. Just do it. Accordingly, members having the same configuration and function as those of the image forming apparatus shown in FIG.

  In the image forming apparatus shown in FIG. 2, an intermediate transfer member 21 is provided so as to face the photosensitive drum 1, and a toner image formed on the photosensitive drum 1 is intermediate transferred by a transfer roller 5 constituting a primary transfer unit. It is transferred to the body 21. The toner image on the intermediate transfer member 21 is transferred by a secondary transfer roller 22 to a transfer material P fed at a predetermined control timing from a transfer material conveying means (not shown). A positive transfer bias having a polarity opposite to the negative polarity that is the normal charging polarity of the toner, +2 kV in this embodiment, is applied to the transfer roller 22 from the power source S4 controlled by the CPU 9.

(F) Developer (toner) replacement means As described in the section of the developing means, the toner in the developer 4e is replenished, charged by stirring and rubbing, and sequentially developed. Although the toner is replaced, if the replacement is small, the toner is excessively charged.

  Therefore, in this embodiment, by forcibly consuming the toner, the toner is forcibly replaced to prevent excessive charging of the toner and to prevent deterioration of the image quality.

  The forced consumption of toner is performed as follows.

  In the image forming apparatus 100 shown in FIG. 1, first, with the transfer roller 5 sufficiently separated from the photosensitive drum 1, the photosensitive drum 1 rotating by the charging roller 2 is charged in the same manner as during image formation.

  Next, the laser beam scanner 3 irradiates the photosensitive drum 1 with a laser beam L corresponding to the irradiation amount FFH within a predetermined range. The developing bias is applied from the power source S2 controlled by the CPU 9 while the portion irradiated with the laser light L on the photosensitive drum 1 passes through the position (developing portion c) facing the developing sleeve 4b. A toner image is formed on the photosensitive drum 1 by rotating the sleeve 4b.

  The toner image developed in this way is not transferred to the transfer material P, but is completely removed by the cleaning device 7.

  Further, during or after the toner is consumed, the consumed amount of toner is supplied from the toner supply tank 4g into the developing container 4a. Accordingly, the toner in the developing container 4a is replaced, and the fluidity and charge amount of the toner become appropriate. Thereby, image deterioration can be effectively prevented.

  Further, the laser irradiation amount is not necessarily FFH, but may be an amount that can develop the toner to some extent efficiently.

  In the case of the image forming apparatus 100 using the intermediate transfer member 21 shown in FIG. 2, the consumed toner does not necessarily have to be removed by the cleaning device 7 provided on the photosensitive drum 1. For example, it may be configured such that after being transferred to the intermediate transfer member 21, it is removed by an intermediate transfer member cleaning device 23 disposed on the intermediate transfer member 21.

  As described above, since the toner is forcibly consumed by removing the toner image without transferring it to the transfer material, image deterioration can be prevented without outputting an unnecessary transfer material.

  Further, by adopting a configuration in which the toner image is removed by the existing cleaning devices 7, 23, etc., it is possible to effectively use the conventional configuration device and prevent image deterioration.

(G) Image information processing means An image information signal sent from an output device such as an image scanner (not shown) or a computer (not shown) via the image information processing device 8 is Is received by the control means (CPU) 9. The CPU 9 controls the operation of the image forming apparatus 100 and controls the laser beam scanner 3 to emit a laser for forming an electrostatic latent image. It should be noted that other light emitters such as light emitting diode elements can also be used for latent image formation. Further, the image forming apparatus itself may be controlled by another CPU.

  The electrostatic latent image is formed in 600 dots per inch (600 dpi) in the axial direction and the rotational direction of the photosensitive drum 1. The depth of each dot is determined by the amount of laser light irradiation, and more toner adheres to the dot where the electrostatic latent image is deeply dug. That is, as the amount of laser light irradiation increases, the output image density increases.

  There are 256 levels of laser light irradiation by the CPU 9, and this is displayed in two hexadecimal digits from 00H to FFH per dot. 00H is the lowest density portion (white background) on the image, and FFH is the highest density portion (solid).

  Here, the sum of all the values from 00H to FFH used for toner consumption regardless of output to the transfer material (automatic control or the like) is referred to as video count data BC (decimal number).

  In this embodiment, a memory is built in the CPU 9 so that an integrated value ΣBC (decimal number) of video count data can be stored.

  Further, in this embodiment, a developer carrying member rotation number accumulating unit 10 is provided for calculating and accumulating the rotation speed of the developer carrier (developing sleeve 4b).

  A specific method for calculating the rotation speed Nsl of the developing sleeve 4b is as follows. The rotation time Tsl (sec) is calculated from the rotation start time and rotation end time of the developing sleeve 4b. Then, using the process speed of the developing sleeve 4b (200 mm / sec in this embodiment) controlled by the CPU 9 and the circumference of the developing sleeve 4b (50 mm in this embodiment), the following is obtained.

  The calculation method of the rotation speed Nsl is not necessarily performed by the calculation method as described above, and may be directly calculated by providing means for detecting the rotation speed of the developing sleeve 4b.

  Further, the integrated value ΣNsl of the developing sleeve 4b is obtained by integrating the rotation speed Nsl of the developing sleeve 4b calculated above. In this embodiment, the integrated value ΣNsl of the rotation speed of the developing sleeve 4b can be stored in a memory built in the CPU 9. Accordingly, the CPU 9 calculates the ratio (hereinafter referred to as “image information signal ratio”) α of the integrated value ΣBC of the video count based on the integrated value ΣNsl of the rotation speed of the developing sleeve 4b.

  Here, the calculation method of the image information signal ratio α will be described in detail with reference to FIG.

  First, the integrated value ΣNsl of the rotation speed of the developing sleeve 4b is multiplied by the circumferential length of the developing sleeve 4b (50 mm in the embodiment) and the length of the developing sleeve 4b in the generatrix direction (300 mm in the embodiment). Obtain the developer consumable range.

  Here, the length in the generatrix direction of the developing sleeve 4b is the width of the developing area of the developing sleeve 4b in the rotation axis direction of the developing sleeve 4b, that is, the width in the sleeve rotating axis direction of the maximum size image that can be formed by the image forming apparatus. Means.

Therefore, the developer consuming range is
Developer consumable range = Developer carrier (developing sleeve) rotation speed integrated value (ΣNsl) × development
Developer at developer circumference (developing sleeve) x maximum image size
Length of carrier (development sleeve) in the direction of the generatrix (development area width)
Is required.

  Then, the integrated value ΣBC of the image information signal (video count data) within the developer consuming range is divided by the image information signal (video count data) when the toner is consumed by the entire FFH dots (full solid). Let (decimal percentage display) be the image information signal ratio α of the image. Note that “full-surface solid” means a state where a dot latent image having the maximum density signal is formed on the entire surface.

That means
Image information signal ratio (α) = {Image information signal (video count data actually consumed developer)
Integrated value)} ÷ {image the entire area where the developer is consumable
Image information signal (video count data)}
It is.

  Accordingly, the image information signal ratio α in the present embodiment can be obtained by the following equation considering that 1 inch = 25.4 mm and the resolution is 600 dpi.

  All of these numerical calculations are processed in the control means (CPU) 9, but it is also possible to separately provide a control means (CPU) and process it.

(H) Control Unit in Developer (Toner) Replacement Mode Next, an actual toner consumption sequence in this embodiment will be described with reference to FIG.

  The number of image outputs is set (step S201). Thereafter, when image formation starts (step S202), the integrated value ΣBC of the video count data input to the CPU 9 is read (step S203). When one image is output (steps S204 and 205), the developing sleeve rotation speed integration means 10 calculates the rotation speed Nsl and integrates the integrated value ΣNsl (step S206). Next, the CPU 9 calculates the image information signal ratio α (step S207).

  It is determined whether the image information signal ratio α is equal to or less than a predetermined reference value (5% in this embodiment) (step S208). If it is 5% or less, that is, if YES, a predetermined amount of toner is consumed and replenished (step S209). In this embodiment, a laser irradiation amount is set to FFH, a latent image for forced developer consumption is formed in the entire axial direction of the photosensitive drum 1, and toner is consumed. Note that this forced developer consumption operation is performed during non-image formation other than the normal image formation operation.

  In this embodiment, the toner consumption is calculated by using the integrated value ΣBC of the video count data and the integrated value ΣNsl of the developing sleeve rotation speed when it is determined that the image information signal ratio α is equal to or less than a predetermined reference value. To calculate. That is, when the toner is consumed with the laser irradiation amount of FFH using the integrated value ΣBC of the video count data and the integrated value ΣNsl of the developing sleeve rotation speed, the laser irradiation until the image information signal ratio α becomes 5%. The amount is calculated by the CPU 9 and the toner is consumed.

  That is, the toner consumption is adjusted by the length of the developing sleeve 4b in the rotation direction. This predetermined amount may be changed each time depending on the image ratio of the output image as in this embodiment, or may be a constant amount. When changing, it is preferable that toner corresponding to the image information signal ratio of 5% or more is consumed together with the image information signal ratio of the output image.

  When a predetermined amount of toner is consumed and replenished, the video count integrated value ΣBC and the developing sleeve rotational speed integrated value ΣNsl are reset and returned to 0 (step S210).

  In this embodiment, the control means 9 is provided with output number counting means for counting the number of output sheets for each output of one image. Of course, the output number counting means may be provided separately from the control means 9 and a signal from the output number counting means may be transmitted to the control means 9.

  Then, the control means 9 checks whether or not the number of output images has reached the designated number after the toner consumption and replenishment are completed (step S211). If the designated number has not been reached, the above processing from reading the video count data is repeated (steps S203 to S211), and if the designated number has been reached, the image formation is terminated (step S212).

  By performing the sequence as described above, a constant amount of toner is always replaced, and it is possible to prevent excessive rubbing of the same toner. In particular, when an image that consumes a small amount of toner is formed, overcharging and deterioration of the toner are suppressed, and the object of the present invention is achieved.

Example 2
Next, a second embodiment of the present invention will be described, particularly regarding the control means in the developer (toner) replacement mode. Other main device configurations are the same as those in the first embodiment.

  In the first embodiment, not only in the image forming mode for outputting one image at a time, but also in the image forming mode for outputting a plurality of the same images continuously, the image ratio is calculated for each output, and the image If the ratio was 5% or less, a predetermined amount of toner was consumed and replenished.

  However, in this embodiment, in the case of the image forming mode in which a plurality of the same images are output continuously, and the image ratio of the images is 5% or less, once for each of the plurality of sheets. Thus, a predetermined amount of toner is consumed and replenished.

  In this embodiment, the same image can be output continuously up to 999 sheets, and the number of sheets to be output continuously within the range up to 999 sheets is designated. When the image information signal ratio of this image is 5% or less, a predetermined amount of toner consumption and replenishment sequence is performed every 100 sheets and when the designated number of sheets is completed.

  That is, when the designated number is less than 100, for example, when 50 is designated, a predetermined amount of toner consumption and replenishment sequence is performed after the 50th sheet is finished. In addition, when the designated number exceeds 100, for example, when 350 is designated, a predetermined amount of toner is consumed and replenished when the 100th, 200th, 300th, and 350th sheets are completed. I do.

  In this embodiment, a laser irradiation amount is set to FFH, a latent image is formed in the entire axial direction of the photosensitive drum 1, and a predetermined amount of toner is consumed. When toner is consumed at the FFH laser irradiation amount using the integrated value ΣBC of the video count data and the integrated value ΣNsl of the developing sleeve rotation speed when it is determined that the image information signal ratio α is equal to or less than a predetermined value. In addition, the CPU 9 calculates the laser irradiation amount until the image information signal ratio α reaches 5%, and the toner is consumed.

  At the end of the toner consumption sequence, the integrated value ΣBC of the video count and the integrated value ΣNsl of the developer carrier rotation speed are reset and returned to zero.

  Further, the amount of toner consumed after image output may be the same as the amount consumed for every 100 sheets, and a constant amount of toner may be consumed regardless of the image ratio of the output image.

  According to the present embodiment, it is possible to optimize the consumption time of a predetermined amount of toner and the execution time of replenishment and prevent a decrease in throughput and the like.

  By performing the sequence as described above, a constant amount of toner is always replaced, and it is possible to prevent excessive rubbing of the same toner. In addition, since the image information signal ratio is calculated based on the rotation speed of the developing sleeve, the developing sleeve is not empty due to different image forming conditions and non-image forming areas that are not considered in the conventional method. Even under environmental conditions with different rotation times, the deterioration of the developer can be accurately captured.

  Here, the calculation result of the image information signal ratio when the sheet interval is different will be described with reference to FIGS.

  In this embodiment, as the image forming mode, the single-side mode shown in FIG. 5 (the distance between sheets when continuous output of A4 size (210 mm in the conveyance direction) paper is 90 mm) and the double-side mode shown in FIG. 6 (A4 size paper). The distance between papers during continuous output is 180 mm). The number of output sheets for single-sided image formation is 26 sheets per minute, and the number of output sheets for double-sided image formation is 20 sheets per minute.

  The process speed of the photosensitive drum 1 and the developing sleeve 4b are different (specifically, the process speed of the developing sleeve 4b is 200/130 times that of the photosensitive drum). Accordingly, the rotation distance of the developing sleeve is 323 mm in the A4 size in the conveyance direction, the distance between sheets in the single-side mode continuous output is 138 mm, and the distance between the sheets in the single-side mode continuous output is 277 mm.

  5 and 6 are image diagrams showing the state of image formation when continuous image formation is performed in the single-sided mode (FIG. 5) and double-sided mode (FIG. 6), respectively, within the developer consumable range for 1 minute. .

  Here, the conventional image ratio, that is, an image in which the ratio of the total area of the toner image to the surface area of the transfer material is 3% is continuously formed.

  5 and 6, the image information signal ratios in the cases of FIGS. 5 and 6 are 2.07% (FIG. 5) and 1.60% (FIG. 6), respectively, and are calculated as the same in the conventional method. The image ratio that has been used can be calculated as an image information signal ratio in consideration of the actual rotation speed of the developing sleeve.

  In particular, when an image that consumes a small amount of toner is imaged under an image forming condition with a long paper interval or an environmental condition in which automatic control is likely to be performed (or the control time is likely to be long), Deterioration is suppressed and the object of the present invention is achieved.

Example 3
Next, a third embodiment of the present invention will be described with reference to FIG. 7 for controlling means for the developer (toner) replacement mode. The other main device configuration is the same as that of the second embodiment.

  In this embodiment, a memory is provided in the CPU 9 so that the number of output sheets after a predetermined amount of toner consumption and replenishment can be stored.

  That is, when image output starts (step S301), the input integrated value ΣBC of the video count is read into the CPU 9 (step S302). When the image output is completed (step S303), the developing sleeve rotational speed calculating means 10 reads the integrated value ΣNsl of the rotational speed of the developing sleeve 4b into the CPU 9 (step 304).

  Next, a variable K indicating the number of output sheets after the predetermined amount of toner consumption and replenishment is read from the memory in the CPU 9, and it is checked whether or not the value of the variable K has reached 100. Since this variable K is expressed as 100 when a value of 100 or more is input, when K is 100, at least 100 sheets have been consumed since a predetermined amount of toner was consumed and replenished last. During this period, predetermined toner consumption and replenishment were not performed.

  Therefore, if K = 100 (step S305), the image information signal ratio data is read from the CPU 9 (step S306). If it is determined that the value is 5% or less (step S307), a predetermined amount of toner is consumed and replenished in the same manner as in the second embodiment (step S308). Thereafter, the integrated value ΣBC of the video count and the integrated value ΣNsl of the rotational speed of the developing sleeve 4b are returned to 0 (step 309). Further, the value of K is returned to 0 (step S310), and the sequence is terminated.

  On the other hand, if K is 99 or less (step S305), the number of output sheets after the previous predetermined amount of toner consumption has not reached 100 sheets, so the value of K is increased by 1 (step S311). The image output is finished as it is.

  According to the present embodiment, it is possible to optimize the consumption time of a predetermined amount of toner and the execution time of replenishment and prevent a decrease in throughput and the like.

  By performing the sequence as described above, a constant amount of toner is always replaced, and it is possible to prevent excessive rubbing of the same toner. In addition, since the image information signal ratio is calculated based on the rotation speed of the developing sleeve, the developing sleeve is not empty due to different image forming conditions and non-image forming areas that are not considered in the conventional method. Even under environmental conditions with different rotation times, the deterioration of the developer can be accurately captured. In particular, when an image that consumes a small amount of toner is imaged under an image forming condition with a long paper interval or an environmental condition in which automatic control is likely to be performed (or the control time is likely to be long), Deterioration is suppressed and the object of the present invention is achieved.

  Although three embodiments according to the present invention have been described above, the developer is not necessarily a two-component developer, and may be a one-component developer. Further, the image information signal ratio that requires toner consumption, the predetermined amount of toner to be consumed, the number of consumed and replenished operations, etc. are not necessarily limited to this.

As explained above,
(1) According to the present invention, the developer is forcibly consumed in accordance with the image information signal ratio calculated based on the rotation speed of the developer carrier. Therefore, even if the image forming conditions which are not considered in the conventional method are different image formation conditions (non-image forming areas) and the environmental conditions are different in the idle rotation time of the developer carrier by automatic control, the developer is accurately deteriorated. Therefore, the developer can be prevented from deteriorating. In particular, even when an image that consumes a small amount of developer is formed under an image forming condition with a long interval between papers or under an environmental condition in which automatic control is easily performed (or control time is likely to be long), the developer. Can be guaranteed. Further, it is possible to continuously output a high-quality image over a long period of time without excessive charging by rubbing the same developer many times.

Furthermore, it is as follows when the effect brought about by the structure demonstrated in the said Example demonstrated above is put together.
(2) When the developer (toner) is forcibly consumed, the same amount of toner as the consumed toner is replenished, so that the toner is replaced and image deterioration can be prevented.
(3) Since the electrostatic latent image on the image carrier is developed as a toner image and the toner image is removed without being transferred to the transfer material, the toner is forcibly consumed, so an unnecessary transfer material is output. Therefore, image degradation can be prevented.
(4) The toner image is removed by means of removing toner remaining on the image carrier that has not been transferred to the image carrier during image formation. Can be prevented.
(5) The magnitude of the image information signal ratio is determined based on the image density information at a predetermined timing. When it is determined that the image information signal ratio is lower than the predetermined value, the toner is forcibly consumed, so that the time spent by the forcible toner consumption operation is optimized and smooth image formation is performed. be able to.
(6) Since the timing is before the next image is output when it is determined that the image information signal ratio is lower than the predetermined value when the image is output, it prevents the speeding up of image formation. And good image formation can be performed.
(7) The above timing is determined to be after the output of the set number of sheets is completed and the image information signal ratio is lower than a predetermined value when the set continuous image formation is performed. When it was done. Therefore, it is possible to appropriately replace the toner without hindering speeding up of image formation.
(8) The timing is determined to be after a predetermined number of images have been output and the image information signal ratio is lower than a predetermined value when a plurality of set continuous images are formed. Is the time. Therefore, it is possible to appropriately replace the toner without hindering speeding up of image formation.
(9) A means for counting the number of output sheets since the last forced toner consumption is provided. The control means for forcibly consuming the toner executes the forcible consumption of the toner based on the image information signal ratio when the total number of output sheets by the means for counting the number of output reaches a predetermined value. It is set to determine whether or not to do. Therefore, it is possible to appropriately replace the toner without hindering speeding up of image formation.

1 is a schematic configuration diagram illustrating an embodiment of an image forming apparatus according to the present invention. It is a schematic block diagram explaining the other Example of the image forming apparatus which concerns on this invention. It is a figure explaining the calculation method of the image information signal ratio of one Example according to this invention. It is a figure explaining operation | movement of the image forming apparatus according to one Example of this invention. It is a figure explaining the calculation method of the image information signal ratio of the other Example according to this invention. It is a figure explaining the calculation method of the image information signal ratio of the other Example according to this invention. It is a figure explaining operation | movement of the image forming apparatus according to the other Example of this invention. It is a schematic block diagram of the image forming apparatus of a prior art example. FIG. 10 is an image diagram for explaining a problem of a toner consumption calculation method based on an image ratio of a conventional image forming apparatus.

Explanation of symbols

1 Photosensitive drum (image carrier)
2 Charging roller (charging means)
3 Laser beam scanner (exposure equipment)
4 Developing device (Developing means)
4b Development sleeve (developer carrier)
5 Transfer roller (transfer means)
6 Fixing device 7 Cleaning device (cleaning means)
8 Image information processing device 9 CPU (control means)
10 Developer carrying member rotation speed integrating means 21 Intermediate transfer body 22 Secondary transfer roller (secondary transfer means)
100 Image forming apparatus

Claims (10)

An image carrier on which an electrostatic image corresponding to the image information signal is formed;
A developer container that stores the developer, and a developer that is rotatably disposed in the developer container, carries and conveys the developer housed in the developer container, and develops an electrostatic image on the image carrier. A developing device comprising a carrier;
In an image forming apparatus having
Image information signal integrating means for integrating the image information signal;
A developer carrying member rotational speed integrating means for calculating and integrating the rotational speed of the developer carrying member;
Developer forcible consumption means for forcibly consuming the developer without outputting it as an image;
Control means for controlling the developer forcible consumption means based on the integrated value from the developer carrier rotation speed integrating means and the integrated value from the image information signal integrating means;
An image forming apparatus comprising:   The control means is based on the ratio (α) of the integrated value from the image information signal integrating means to the developer consumable range calculated based on the integrated value from the developer carrier rotational speed integrating means. The image forming apparatus according to claim 1, wherein the forced developer consumption unit is controlled. The developer consuming range is
Developer consumable range = developer carrier rotation speed integrated value x developer carrier circumference x maximum image size
Determined by the length in the direction of the developer carrier in
The ratio (α) is
Ratio (α) = (Integrated value of image information signal that actually consumed developer) ÷ (Developer consumable range)
(Image information signal when a full image is created)
The image forming apparatus according to claim 2, wherein the image forming apparatus is an image forming apparatus.   The apparatus further comprises means for replenishing the developer container with the same amount of developer as the developer consumed by the operation of the developer forced consumption means at the same time as or after the operation of the developer forced consumption means. The image forming apparatus according to claim 1. A transfer means for transferring the developer image on the image carrier to a transfer material directly or via an intermediate transfer member;
The developer forcible consumption means forms an electrostatic image for forced consumption on the image carrier, develops the electrostatic image with the developing device to form a developer image, and the developer on the image carrier Without transferring the image to the transfer material, or after transferring the developer image on the image carrier to the intermediate transfer member, the image is not transferred from the intermediate transfer member to the transfer material. The image forming apparatus according to claim 1, wherein the image forming apparatus is removed from the intermediate transfer member.   Cleaning means for removing the developer remaining on the image carrier or the intermediate transfer member that has not been transferred to the transfer material and remaining on the image carrier without being transferred onto the image carrier at the time of image formation Alternatively, the image transfer member or the intermediate transfer member is removed by a cleaning unit that removes a transfer residual developer remaining without being transferred onto the intermediate transfer member. Image forming apparatus.   3. The control means for controlling the developer forced consumption means is set to execute the developer forced consumption means based on the ratio at a predetermined timing. 7. The image forming apparatus according to any one of items 6.   The image forming apparatus according to claim 7, wherein the timing is before a next image is output when it is determined that the ratio is lower than a reference value when the image is output.   The timing is after a set number of sheets have been output and when the ratio is determined to be lower than the reference value when continuous image formation of a set number of sheets is performed. The image forming apparatus according to claim 7, wherein the image forming apparatus is provided.   The timing is when a predetermined number of images are formed and when a predetermined number of images are output and when the ratio is determined to be lower than the reference value. The image forming apparatus according to claim 9, wherein the image forming apparatus is provided.