JP2006065078A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus of a small type, with which an image can be formed right after a developing device or a process cartridge is attached to the main body of the image forming apparatus. <P>SOLUTION: The image forming apparatus includes the developing device, a developer supply means, and a developer supply control means. The developing device has a development container and a developer face detecting means. The initial amount of developer, which is an amount of unused developer stored in the development container of the developing device, is smaller than an amount of developer corresponding to the developer face at the prescribed level. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the present invention, for example, an electrostatic latent image formed on an image carrier using an electrophotographic system or an electrostatic recording system is visualized by using a developing device to form a visible image. The present invention relates to an image forming apparatus that obtains a permanent image by being transferred and fixed thereon.

  Here, the electrophotographic image forming apparatus includes, for example, a copying machine, a printer (for example, an LED printer, a laser beam printer, etc.), a facsimile apparatus, and a word processor.

  The process cartridge is a cartridge in which a charging means, a developer carrier or a cleaning means and an electrophotographic photosensitive member (image carrier) are integrally formed, and the cartridge can be attached to and detached from the image forming apparatus main body. It is. Alternatively, at least one of the charging unit, the developer carrying member, and the cleaning unit and the electrophotographic photosensitive member are integrally formed into a cartridge that can be attached to and detached from the image forming apparatus main body. Alternatively, it means that at least the developer carrying member and the electrophotographic photosensitive member are integrated into a cartridge so as to be detachable from the image forming apparatus main body.

  Conventionally, dry development is generally employed in an image forming apparatus using an electrophotographic system. There are two types of dry development: a two-component development method using a toner containing a carrier (magnetic powder such as iron powder and ferrite) and a one-component development method using a toner not containing a carrier. One-component development methods are becoming mainstream mainly in small copying machines.

  A single-component development type developing device may have a simpler configuration than the two-component development type, and is advantageous for cost reduction and size reduction. In addition, to reduce running costs and reduce environmental impact, a separate toner cartridge is provided to extend the life of process parts such as photoconductors, charging members, developer carriers, and cleaning members, and to supply toner to the developing device. The so-called toner replenishment type configuration provided is the mainstream.

  FIG. 10 is a cross-sectional view showing an example of a toner replenishment type image forming apparatus using the one-component development method.

  As shown in FIG. 10, an electrophotographic photosensitive member (hereinafter referred to as “photosensitive drum”) as an image carrier, for example, a photosensitive drum 101, that is, a photosensitive drum 101, is provided at the approximate center of a conventional image forming apparatus. Is supported rotatably in the direction of the arrow.

  When the image forming operation is started, the charging unit 102 uniformly charges the surface of the photosensitive drum 101. Thereafter, for example, a laser irradiation unit 103 as an exposure unit exposes the surface of the photosensitive drum 101 charged with the laser light L corresponding to the image information, and forms an electrostatic latent image on the surface. The developing cartridge 104 visualizes the formed electrostatic latent image with a developer supplied to the photosensitive drum 101 to form a so-called toner image.

  This toner image is electrostatically transferred onto the recording material by a transfer electric field formed between the photosensitive drum 101 and the transfer roller 105 by, for example, a transfer roller 105 as a transfer unit. Thereafter, the unfixed toner image on the recording material is fixed on the recording material by heat and pressure in the fixing device 106.

In addition, transfer residual toner remaining on the surface of the photosensitive drum 101 after the transfer of the toner image is removed by, for example, a cleaning device 108 including a blade-like cleaning member 107, and the photosensitive drum 101 can continue to form an image. It becomes.

  Next, the developing cartridge 104 used in the conventional image forming apparatus will be described.

  The developing cartridge 104 is a developing device that is detachably attached to the image forming apparatus, and a nonmagnetic one-component developer (hereinafter referred to as toner 111) as a developer is accommodated in the developing container 113.

  Further, the developing container 113 is partially open on the side facing the photosensitive drum 101, and a developing roller 114 as a developer carrying member is rotatably supported so as to be partially exposed from the opening. ing.

  The supply roller 116 as a developer supply / collection means is formed of, for example, a sponge roller as an elastic body, and is provided so as to rotate in contact with the development roller 114.

  As the developing roller 114 and the supply roller 116 slide, the toner 111 is charged by friction. The toner 111 to which a charge is applied in the rubbing region between the developing roller 114 and the supply roller 116 is supplied onto the developing roller 114 by receiving a mirroring force by the charged charge. Further, a blade 117 as a developer layer thickness regulating member is provided in the developing container 113 so as to press the developing roller 114.

  Further, the toner 111 on the developing roller 114 passes through a contact area with the blade 117 as the developing roller 114 rotates, so that the layer thickness is regulated and applied to the developing roller 114 in a thin layer.

  Further, the toner 111 is given a sufficient charge for development upon friction between the developing roller 114 and the blade 117. Thereafter, as the developing roller 114 rotates, the toner 111 is conveyed to a developing area (developing nip) where the photosensitive drum 101 and the developing roller 114 are in contact with each other.

  On the other hand, a voltage is applied to the developing roller 114 from a power source (not shown) between the photosensitive drum 101 and the developing roller 114, and a developing electric field is formed between the photosensitive drum 101 and the photosensitive drum 101. Accordingly, the toner on the developing roller 114 is transferred to the electrostatic latent image on the photosensitive drum 101 by the action of the developing electric field, and a toner image is formed on the photosensitive drum 101.

  At this time, of the toner applied on the developing roller 114 and carried and conveyed to the developing nip, the toner remaining on the developing roller 114 without contributing to the development is a supply roller (developer supply and stripping means). The toner is peeled off from the developing roller 114 by the rubbing 116, and a part of the toner is supplied to the developing roller 114 again by the supplying roller 116 together with the toner 111 newly supplied to the supplying roller 116, and the remaining is the developing container 113. Returned in.

  Next, a toner replenishing operation to the developing cartridge 104 will be described.

  In the developing cartridge 104, a toner level sensor 118 using a pressure sensor as described in Patent Document 1 is provided on the inner surface of the developing container 113.

The toner level sensor 118 is a sensor for detecting the level of the toner 111 in the developing container 113. When the toner level in the developing container 113 falls below a predetermined level, the toner as a developer storage container The cartridge 112 is controlled to replenish toner by the rotational driving of the replenishing roller 119.

  Then, when the toner level sensor 118 determines that the detected surface level of the toner 111 has reached a predetermined level, control is performed to stop the rotation of the replenishing roller 119.

  The toner stirring member 120 is a stirring member for uniformly distributing the toner 111 remaining in the developing cartridge 104 and the newly replenished toner 111, and also serves to equalize the level of the toner agent surface. Since toner replenishment control is sequentially performed according to the amount of toner in the developing cartridge 104 in this way, the toner 111 in the developing cartridge 104 can always maintain a stable surface, and as a result, the toner in the developing cartridge 104 is insufficient. Therefore, it is possible to avoid the white-out phenomenon of the image and the toner deterioration due to the frequency with which the residual toner is rubbed between the developing roller 114 and the supply roller 116.

  Further, since the amount of toner in the developing container 113 becomes excessive, the load on the supply roller 116 increases, and problems such as toner clogging and an increase in rotational torque can be avoided.

  However, the image forming apparatus may have the following problems.

  That is, since the developer cartridge 104 is configured to sequentially supply toner, the developer cartridge 104 contains in advance the toner 111 corresponding to the toner agent surface level within a certain range.

  FIG. 11 shows a schematic configuration diagram of the developing cartridge 104 in the conventional example when not in use. A new developer cartridge 104 that is not used has a toner seal member 121 that prevents the toner from flowing into the developing roller 114 and the supply roller 116 so that the toner 111 does not leak from the developing cartridge 104 during transportation or the like. Is provided.

  By removing the toner seal member 121 before the use of the developing cartridge 104, the toner 111 flows into the developing roller 114 and the supply roller 116 and becomes usable. However, the provision of the toner seal member 121 inevitably increases the volume of the developing container 113. As a result, the image forming apparatus main body 109 itself is also increased in size. In particular, the influence is large in a color image forming apparatus having a plurality of image forming units.

  Further, since a predetermined amount of toner 111 is accommodated in the developing cartridge 104 in advance, an increase in weight and cost increase are caused, which is not preferable for the user.

  Furthermore, there is a problem that it takes time to fill the toner in the manufacturing process. In order to avoid such a problem, toner is not replenished in the unused developing cartridge, but is supplied to the image forming apparatus main body until the toner surface reaches a predetermined level prior to image formation. A method of performing image formation and then starting image formation is conceivable. However, this case is not preferable for the user because it takes time until image formation becomes possible.

  On the other hand, there is a type that replenishes the toner stored in the toner cartridge into the developing cartridge all at once. In this configuration, since the toner necessary for image formation is replenished immediately after the developing cartridge is mounted on the main body of the image forming apparatus, it is not necessary to previously store the toner in the unused developing cartridge. As a result, the developing cartridge does not become larger than necessary.

However, in such a configuration, since new toner is not replenished while image formation is repeated, there is a possibility of toner deterioration due to toner reduction in the developing cartridge as described in the conventional example.
JP 7-253709 A

  The present invention has been made in view of the above prior art, and an object of the present invention is to provide a small-sized image forming apparatus capable of forming an image immediately after a developing device or a process cartridge is mounted on the image forming apparatus main body. It is in.

In order to achieve the above object, in the image forming apparatus according to the present invention,
An image carrier on which an electrostatic latent image is formed;
A developing device for developing the electrostatic latent image;
Developer supplying means for supplying developer to the developing device;
Developer supply control means for controlling the drive of the developer supply means;
In an image forming apparatus comprising:
The developing device includes:
A developer container containing a developer;
A developer carrying member provided in an opening of the developing container, carrying and transporting the developer, and developing an electrostatic latent image on the image carrying member in contact with or close to the image carrying member. A developer carrier;
Developer surface detecting means for detecting the developer surface stored in the developer container,
The developer replenishment control means controls the driving of the developer replenishment means so as to maintain the developer surface at a predetermined level according to the detection result by the developer surface detection means.
The initial developer amount stored in the developing container of the developing device when not in use is smaller than the developer amount corresponding to the developer surface at the predetermined level.

  According to the present invention, it is possible to provide a small-sized image forming apparatus capable of forming an image immediately after the developing device and the process cartridge are mounted on the main body of the image forming apparatus.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings and embodiments. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. . Further, the materials, shapes, etc. of the members once described in the following description are the same as those in the first description unless otherwise described.

  FIG. 1 is a cross-sectional view illustrating a schematic configuration of a laser beam printer which is an embodiment of an image forming apparatus according to the present embodiment.

  The image forming apparatus main body 9 according to this embodiment includes an image carrier (hereinafter referred to as “photosensitive drum”) 1 which is a drum-shaped electrophotographic photosensitive member on which an electrostatic latent image is formed, and an electrostatic latent image. A developing cartridge 4 for developing, a developer supplying means 19 for supplying developer to the developing cartridge 4, and a developer supplying control means for controlling the driving of the developer supplying means 19 are provided. Here, as the developer replenishment control means, for example, a CPU or a dedicated electric circuit can be used. Below, the case where CPU22 is used as a developer replenishment control means is demonstrated (refer FIG. 6).

  The image forming apparatus main body 9 supports the photosensitive drum 1 so as to be rotatable in the direction of the arrow at substantially the center thereof. When the image forming operation starts, the charging roller 2 uniformly charges the surface of the photosensitive drum 1. Thereafter, the laser irradiation means 3 as an exposure means exposes the surface of the charged photosensitive drum 1 with a laser beam L corresponding to the image information, and forms an electrostatic latent image on the surface.

  In this embodiment, the charged charge of the photosensitive drum 1 is negative. The portion where the negative charged charge is attenuated by the exposure of the laser beam L forms an image portion.

  Thereafter, the electrostatic latent image is visualized by the toner 11 supplied from the developing cartridge 4 as the photosensitive drum 1 rotates, and a so-called toner image is formed on the photosensitive drum 1.

  In this embodiment, the development is performed by reversal development, and toner having the same polarity (negative polarity) as the charged charge adheres to the image portion on the photosensitive drum 1 where the negative charge is attenuated.

  On the other hand, the recording material fed into the image forming apparatus by the paper feed roller reaches the transfer area where the photosensitive drum 1 and the transfer roller 5 as a transfer unit abut, and the toner image on the photosensitive drum 1 reaches the transfer area. It is conveyed synchronously.

  When the toner image on the photosensitive drum 1 and the recording material reach the transfer area, the toner image is transferred onto the recording material by the transfer electric field formed in the transfer area by the transfer roller 5. Thereafter, the unfixed toner image carried on the recording material is fixed as a permanent image on the recording material by being heated by a fixing means (heat roller) 6a provided in the fixing device 6 and pressurized by a pressure means 6b. The

  Further, after the transfer of the toner image is completed, the transfer residual toner remaining on the surface of the photosensitive drum 1 is removed by the cleaning device 8 including the blade-shaped cleaning unit 7 to prepare for the subsequent image forming operation.

  Next, the developing device (developing cartridge) will be described with reference to FIG. FIG. 2 is a cross-sectional view of a main part of the developing cartridge and the toner cartridge that can be attached to and detached from the image forming apparatus main body.

  In the image forming apparatus main body 9 according to the present embodiment, the developing cartridge 4 as a developing device is configured to be detachable so as to be replaceable with respect to the image forming apparatus main body 9. Hereinafter, this developing device is referred to as a developing cartridge 4.

  The developing cartridge 4 is a developing container 13 that contains toner, and a developing roller 14 that is provided in an opening of the developing container 13. The developing cartridge 4 carries and carries the toner, and contacts or approaches the photosensitive drum 1. A developing roller 14 as a developer carrying member for developing the electrostatic latent image on the upper side, a supply roller 16 as a developer supply means for supplying toner to the developing roller 14, and the toner supplied by the supply roller 16 are regulated. A blade 17 as a developer regulating means for forming a toner layer on the developing roller 14, a toner level sensor 18 as a developer surface detecting means for detecting the toner surface contained in the developing container 13, and a developing container. 13 and a toner stirring member 20 as a developer stirring means for uniformly dispersing the toner and leveling the toner surface.

  Further, in the image forming apparatus main body 9 according to the present embodiment, the toner cartridge 12 that replenishes the toner 11 into the developing cartridge 4 via the replenishing unit 10 and is configured to be detachable from the image forming apparatus main body 9. Is provided.

In the developing cartridge 4 according to this embodiment, a negatively chargeable non-magnetic one-component developer (hereinafter referred to as toner 11) as a developer is accommodated in a developing container 13. Developer cartridge 4
The developing container 13 is partially open on the side facing the photosensitive drum 1, and the developing roller 14 is rotatably supported by the developing container 13 so as to be partially exposed from the opening.

  The developing roller 14 includes an elastic body and is in contact with the photosensitive drum 1 with a predetermined contact pressure. Further, a blowout prevention sheet 15 is provided at the opening of the developing container 13 in order to prevent the toner 11 from scattering from the lower portion of the developing roller 14.

  A supply roller 16 as a means for supplying and collecting toner to the developing roller 14 is a sponge roller as an elastic body, and is disposed in contact with the developing roller 14. The supply roller 16 is rotatably supported by the developing container 13, and a charge is imparted to the toner by frictional charging accompanying sliding friction with the developing roller 14.

  In this way, the charged toner 11 is supplied onto the developing roller 14 by receiving a reflection force from the developing roller 14 by the charged charge. Further, the developing container 13 is provided with a blade 17 so as to pressurize the developing roller 14, and the toner 11 supplied onto the developing roller 14 has its layer thickness regulated by the blade 17 and is applied. Thus, a thin layer of toner is formed on the developing roller 14. Further, at this time, the toner is given a sufficient charge to be used for development due to friction with the surfaces of the developing roller 14 and the blade 17.

  Thereafter, the toner thin layer on the developing roller 14 is conveyed to a developing region (developing nip) where the photosensitive drum 1 and the developing roller 14 come into contact with the rotation of the developing roller 14, and the toner 11 is transferred to the photosensitive drum 1. It is used for development in a state of contact with

  That is, a power source (not shown) is connected so that a developing electric field is formed between the photosensitive drum 1 and the developing roller 14, and the toner on the developing roller 14 is applied to the photosensitive drum 1 by the action of the developing electric field. Then, a so-called toner image is formed on the photosensitive drum 1 and the electrostatic latent image is visualized.

  Further, the toner applied on the developing roller 14 and carried and transported to the developing nip does not contribute to the development, and the toner further carried on the developing roller 14 is rubbed by the supply roller 16 by the rubbing by the supply roller 16. 14 is peeled off from above and returned to the developing container 13.

  Next, the toner supply operation will be described.

  A toner level sensor 18 is provided in the developing container 13 and detects the level of the surface of the toner 11. In this embodiment, the CPU 22 drives the developer replenishing means 19 so that the surface of the toner 11 is maintained at a predetermined level in accordance with the detection result of the surface level of the toner 11 detected by the toner level sensor 18. And the toner supply to the developing cartridge 4 is controlled. Here, the toner level sensor 18 uses a piezoelectric element, and detects the surface level of the toner 11 based on a change in the toner pressure on the surface thereof.

  The toner level sensor 18 is not limited to a piezoelectric element. For example, as long as it can detect the surface level of the toner 11 accommodated in the developing container 13, for example, light transmission type detection, pressure conductive sheet It is possible to replace with any sensor using a capacitor.

The toner level sensor 18 detects the level of the toner 11 in the developing container 13 during a series of apparatus operations associated with image formation. When it is detected that the surface level of the toner 11 detected by the toner level sensor 18 is lower than a predetermined level (lower limit value), the CPU 22 starts the drive control of the developer replenishing means 19 and puts it in the toner cartridge 12. The accommodated toner 11 is replenished into the developing container 13 of the developing cartridge 4.

  Thereafter, when the surface level of the toner 11 reaches a separately set predetermined level (upper limit value), the drive of the developer replenishing means 19 is controlled to stop the toner replenishment. In this way, by detecting the level of the toner 11 in the developing container 13 and controlling the toner supply, the level of the toner 11 can always be stabilized.

  That is, it is possible to maintain the surface level of the toner 11 that does not cause problems such as toner deterioration described later, toner clogging of the supply roller 16, and an increase in rotational torque. Further, in order to accurately detect the surface level of the toner 11, a toner stirring member 20 for leveling the surface of the toner is provided.

  The toner stirring member 20 also serves to stir and mix the toner 11 accommodated in the developing container 13 and the toner newly supplied by the developer supply means 19.

  In this embodiment, the replenishment operation is started when the toner surface level corresponding to 180 g of toner in the developing container 13 is detected, and the replenishment operation is performed when the toner surface level corresponding to 200 g is reached. Supply control is performed to stop.

  The upper and lower limit values of the toner surface level are set for the reasons described below.

  The lower limit value of the toner surface level of the toner is set such that the toner 11 staying in the developing container 13 without being used for a long period of time due to repetition of the image forming operation is, for example, between the developing roller 14 and the supply roller 16. It is determined for the purpose of preventing toner deterioration caused by rubbing many times. That is, it is preferable that as much toner as possible is accommodated in order to reduce the rubbing frequency. In this embodiment, it is known that the toner amount is not deteriorated even when used for a long time by securing the toner amount of 180 g.

  On the other hand, the setting of the upper limit value of the toner agent surface level is determined based on the load limit to the supply roller 16. In this embodiment, by setting the amount of toner in the developing container 13 to 200 g or less, toner clogging to the supply roller 16 made of a sponge member and increase in rotational torque do not occur.

  The upper and lower limits of the toner agent surface level are determined based on the above-described standards. Of course, the present invention is not limited to these standards, and a developing container that does not generate a blank image due to lack of toner. For reasons such as preventing toner overflow from 13, the upper and lower limits of the toner agent level may be provided.

  The image forming operation of this embodiment is performed by the series of operations described above.

  Next, the developing cartridge when not in use, which is a feature of this embodiment, will be described with reference to FIG. The developing cartridge 4 shown in FIG. 3 is a schematic configuration diagram of the developing cartridge 4 described in FIGS. 1 and 2 before use (that is, new). When not in use, a seal member 21 is provided in a part of the developing container 13 in order to prevent toner from flowing out toward the developing roller 14 and the supply roller 16.

The seal member 21 is disposed between the developing roller 14 and the blade 17 or the blowout prevention sheet 15 between the developing roller 14 and the developing cartridge 4 due to vibration and impact during transportation from the manufacturer to the store and from the store to the user. It is possible to prevent leakage to the outside.

  Here, in this embodiment, the unused initial toner amount stored in the developing container 13 of the developing cartridge 4 is the predetermined level of the developing container 13 during the normal image forming operation described above. It is characterized by being less than the developer amount corresponding to the toner agent surface.

  In other words, the new developing cartridge 4 shown in FIG. 3 contains only 150 g of toner 11 as an initial toner amount. Therefore, the developing cartridge 4 according to this embodiment has an unnecessarily large developing container 13 as compared with the case where 200 g of toner 11 that is the toner amount in the developing container 13 that is stably maintained during the image forming operation is stored in advance. Since the internal volume does not increase, the size can be reduced.

  Next, an initial replenishment operation when the new developing cartridge 4 is used and mounted on the image forming apparatus main body 9 will be described with reference to a flowchart and a block diagram. FIG. 5 is a flowchart of the initial supply operation in the image forming apparatus according to the present embodiment. FIG. 6 is a block diagram relating to the initial supply operation according to the present embodiment.

  In the new developer cartridge 4, when the user removes the seal member 21 during use, the toner 11 in the developer container 13 falls to the developing roller 14 and the supply roller 16 side, and the usable state as shown in FIG. Become.

  Thereafter, when the image forming apparatus body 9 is mounted, the toner level surface V is detected by the toner level sensor 18 (step S1). The CPU 22 starts driving the developer replenishing means 19 so that the toner agent surface reaches a predetermined level according to the detection result by the toner level sensor 18, and the developing cartridge 4 is replenished with toner (step S2, S2). S3). The toner level sensor 18 sequentially detects the toner surface level V (step S4) and compares it with a predetermined upper limit value (step S5). When the detected toner surface level V is smaller than the toner surface level corresponding to the upper limit value 200 g (No), toner supply to the developing cartridge 4 is performed until the toner surface level reaches the toner surface level corresponding to the upper limit value 200 g. Will continue. On the other hand, when the detected toner surface level V is equal to or higher than the toner surface level corresponding to the upper limit value 200 g, the CPU 22 stops driving the developer replenishing means 19 and replenishes toner to the developing cartridge 4 during the initial replenishment operation. The operation is stopped (step S6).

  Thereafter, a normal replenishment operation is started, and the replenishment operation is performed so that the toner agent surface falls between the toner agent surface level corresponding to the upper limit value of 200 g and the toner agent surface level corresponding to the lower limit value of 180 g. It is done repeatedly.

  The control of the initial replenishment operation described above may be performed during the image forming operation as in normal use after the new developing cartridge 4 is mounted on the image forming apparatus main body 9. In this way, the user does not have to wait for print output until the predetermined toner agent level is reached, compared to the case where image formation is possible after the initial replenishment operation is performed, and image formation is not required. The device can be used immediately.

  Further, in this embodiment, the initial toner amount stored in the new developer cartridge 4 is smaller than 180 g which is the lower limit value during normal replenishment control, but in the initial stage, it is stored in the developer cartridge 4. Since the toner 11 itself is also new, toner deterioration is less likely to occur compared to the toner 11 in the developing container 13 during long-term use. Therefore, the initial toner amount in this embodiment may be set to an amount that does not cause problems such as image blanking due to toner shortage.

  As described above, according to the present invention, the initial toner amount contained in an unused new developing cartridge is configured to be smaller than the predetermined toner agent level maintained during normal image formation. The cartridge can be downsized. As a result, the image forming apparatus main body can also be reduced in size. At the same time, it is possible to improve the productivity by reducing the weight and cost of the developing cartridge and reducing the amount of toner filling during manufacture.

  In addition, according to the present embodiment, the user can replenish toner up to a predetermined toner surface level by adopting a configuration in which toner is replenished during the image forming operation even after the new developing cartridge is mounted on the main body of the image forming apparatus. There is no need to wait for the operation, and printing can be performed immediately.

  Further, although the present embodiment has been described using the developing cartridge, at least the above-described image carrier on which the electrostatic latent image is formed and the developing device are integrally assembled to form the image forming apparatus. It goes without saying that the same effect can be obtained even with a process cartridge configured to be detachable from the main body.

  Further, in a color image forming apparatus having a plurality of developing cartridges or process cartridges, if the developing device of this embodiment is adopted, the effect of miniaturization is great.

  FIG. 7 is a cross-sectional view of an essential part showing a schematic configuration before use (that is, new) of a developing cartridge that can be attached to and detached from the image forming apparatus main body according to the second embodiment. The present embodiment is characterized in that the initial toner amount is further reduced as compared with the developing cartridge described in the first embodiment, and the toner replenishment amount by the developer replenishing means during the image forming operation can be varied.

  The names and operations in the respective process units of the developing cartridge 34 shown in FIG. 7 are the same as those described in the first embodiment, and a detailed description thereof will be omitted. The new developer cartridge 34 according to the second embodiment has a configuration in which the initial toner amount is further reduced as compared with the new developer cartridge described in the first embodiment. Specifically, the initial toner amount is only 100 g.

  8 is a schematic configuration diagram of the image forming apparatus with the developing cartridge 34 mounted in the present embodiment, and FIG. 9 shows a schematic configuration of only the developing cartridge 34 and the toner cartridge 42 immediately after the new developing cartridge is mounted. FIG. Since the normal image forming operation by the image forming apparatus and the developing apparatus of FIGS. 8 and 9 is as described in the first embodiment, the description thereof is omitted.

  The developing cartridge 34 shown in FIG. 9 shows a state immediately after the seal member 51 of the new developing cartridge 34 shown in FIG. 7 is removed and attached to the main body 39 of the image forming apparatus. Is configured to include only the toner 41 to such an extent that no image blank due to toner shortage occurs.

  For this reason, in a normal replenishment operation, for example, a white spot may occur for a user who continuously outputs a high printing rate image with many printing portions for a recording material. Therefore, in this embodiment, in order to avoid the occurrence of white spots in the image, the amount of toner replenishment during the image forming operation immediately after the developing cartridge 34 is mounted on the image forming apparatus main body 39 is increased compared with the normal image forming operation. It is characterized by.

In the developer replenishing means 49 of this embodiment, the toner replenishing amount per unit time can be varied in two stages. That is, a normal supply mode and a quick supply mode are provided, and the quick supply mode has a larger amount of toner supply per unit time than the normal supply mode. The adjustment of the replenishment mode is controlled by changing the rotation speed of a replenishment roller as developer replenishing means 49 by a CPU (not shown).

  The replenishment mode is selected based on the detection result of the toner level sensor 48 which is a developer surface detecting means. Specifically, when the surface level of the toner 41 is lower than the lower limit value of the toner level sensor 48, the quick supply mode is selected, and more toner is supplied than in the normal supply mode. Here, it is desirable that the toner replenishment amount per unit time in the quick replenishment mode is equal to or more than the toner amount consumed per unit time when the entire black printing is performed on the recording material.

  Thereafter, when the toner level sensor 48 detects that the surface level of the toner 41 has reached the lower limit value, the CPU switches to the normal supply mode, and the amount of toner supply per unit time decreases. . By doing so, it is possible to prevent an image blanking phenomenon due to a shortage of toner immediately after the developing cartridge 34 is mounted on the image forming apparatus main body 39, and thereafter, the toner agent level is reduced by reducing the toner replenishment amount. Since fine adjustment is possible, the toner agent surface level can be stably maintained.

  In other words, the CPU according to the present embodiment uses the developer replenishing means so that the toner replenishment amount when the detected level of the toner agent surface is lower than the predetermined level is larger than the toner replenishment amount when the detected level is higher than the predetermined level. 49 is controlled.

  As described above, according to the present embodiment, the initial toner amount contained in the unused new developing cartridge 34 is configured to be smaller than the predetermined toner agent surface level maintained during normal image formation, and Since the toner replenishment amount per unit time by the developer replenishing means 49 can be varied in several stages, the development cartridge 34 and the image forming apparatus main body 39 can be further reduced in size. At the same time, the weight of the developing cartridge 34 can be further reduced, the cost can be reduced, and the productivity can be improved due to the small amount of toner filling at the time of manufacture.

  Further, according to the present embodiment, similarly to the first embodiment, even after the new developing cartridge 34 is attached to the image forming apparatus main body 39, the toner is replenished during the image forming operation, and the image immediately after the attachment is provided. The amount of toner replenished per unit time in the forming operation is greater than that during replenishment during normal image formation, so that even a user who outputs at a high printing rate does not generate white-out images due to toner shortage, and There is no need to wait for a toner replenishment operation up to a predetermined toner agent surface level, and printing output can be performed immediately.

  Further, although the present embodiment has been described using the developing cartridge, at least the above-described image carrier on which the electrostatic latent image is formed and the developing device are integrally assembled to form the image forming apparatus. It goes without saying that the same effect can be obtained even with a process cartridge configured to be detachable from the main body.

  Further, in a color image forming apparatus having a plurality of developing cartridges or process cartridges, if the developing device of this embodiment is adopted, the effect of miniaturization is great.

1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus according to Embodiment 1. FIG. FIG. 3 is a cross-sectional view of main parts of a developing cartridge and a toner cartridge that can be attached to and detached from the image forming apparatus main body according to the first exemplary embodiment. FIG. 3 is a cross-sectional view of a main part of the developing cartridge when not in use (new article) according to Embodiment 1. 1 is a cross-sectional view of a main part of a new developing cartridge immediately after being mounted on an image forming apparatus main body according to Embodiment 1. FIG. 3 is a flowchart of an initial supply operation in the image forming apparatus according to the first embodiment. 6 is a block diagram relating to an initial supply operation according to Embodiment 1. FIG. FIG. 6 is a cross-sectional view of a main part of a developing cartridge when not in use (new) according to Embodiment 2. 5 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus main body according to Embodiment 2. FIG. FIG. 6 is a cross-sectional view of a main part of a developing cartridge and a toner cartridge that can be attached to and detached from an image forming apparatus main body according to Embodiment 2. It is sectional drawing which shows schematic structure of the conventional image forming apparatus main body. It is sectional drawing which shows schematic structure of the conventional developing cartridge at the time of unused (new article).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging roller 3 Laser irradiation means 4 Developer cartridge 9 Image forming apparatus main body 11 Toner 12 Toner cartridge 13 Developer container 14 Developer roller 16 Supply roller 17 Blade 18 Toner level sensor 19 Developer supply means 20 Toner stirring member 22 CPU ( Developer replenishment control means)

Claims (8)

An image carrier on which an electrostatic latent image is formed;
A developing device for developing the electrostatic latent image;
Developer supplying means for supplying developer to the developing device;
Developer supply control means for controlling the drive of the developer supply means;
In an image forming apparatus comprising:
The developing device includes:
A developer container containing a developer;
A developer carrying member provided in an opening of the developing container, carrying and transporting the developer, and developing an electrostatic latent image on the image carrying member in contact with or close to the image carrying member. A developer carrier;
Developer surface detecting means for detecting the developer surface stored in the developer container,
The developer replenishment control means controls the driving of the developer replenishment means so as to maintain the developer surface at a predetermined level according to the detection result by the developer surface detection means.
An image forming apparatus, wherein an unused initial developer amount stored in a developer container of the developing device is smaller than a developer amount corresponding to the predetermined level developer surface.   The developer replenishment control means controls the developer replenishment means so that the developer is replenished until the developer surface reaches a predetermined level after the developing device is mounted on the image forming apparatus main body. The image forming apparatus according to claim 1, wherein:   The image forming apparatus according to claim 2, wherein the replenishing operation by the developer replenishing unit is performed during the image forming operation. The developer replenishing means is configured such that the developer replenishment amount per unit time can be changed in a plurality of stages.
The developer replenishment control means is configured to supply the developer so that a developer replenishment amount when the detected developer surface level is lower than a predetermined level is larger than a developer replenishment amount when the level of the developer surface is higher than the predetermined level. The image forming apparatus according to claim 1, wherein the image forming apparatus is controlled. The developing device further includes:
Developer supplying means for supplying the developer to the developer carrying member;
Developer regulating means for regulating the developer supplied by the developer supplying means to form a developer layer on the developer carrier;
A developer agitating means movable to mix the developer replenished from the developer replenishing means and the developer in the developer container;
The image forming apparatus according to claim 1, further comprising:   An image forming apparatus comprising a plurality of the developing devices according to claim 1 and forming a color image.   The image forming apparatus according to claim 1, wherein the developing device is configured to be detachable from the image forming apparatus main body.   7. The process cartridge according to claim 1, wherein the image carrier and the developing device are integrally assembled and provided in a process cartridge configured to be detachable from the image forming apparatus main body. The image forming apparatus according to any one of the above.

Images