JP2006084561A - Developing apparatus, image forming apparatus, and process unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for stably obtaining a high quality image, suppressed of the generation of ghosts, at a low cost. <P>SOLUTION: A developing apparatus comprises a development sleeve 41 for carrying a developer, and a developer circulation regulating member 70 for regulating the circulation of the developer, in the neighborhood (substantially downward) of a development blade 42 for regulating the layer thickness of the developer carried on the development sleeve 41. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus having a function of forming an image on a recording medium such as a sheet, for example, a copying machine, a printer, or a facsimile machine. It relates to the process unit.

  In an image forming apparatus using electrophotography, in order to faithfully reproduce an electrostatic latent image on a photoreceptor, there is a jumping development method as one of dry development methods for toner which is a magnetic one-component developer.

  In this jumping development method, a developing sleeve as a developer carrying member is placed opposite to a photosensitive member while maintaining a constant interval (50 to 500 μm), and a developing bias in which direct current and alternating current are superimposed is applied to the developing sleeve. An electric field that reciprocates the toner particles is formed, and the toner applied in a thin layer on the developing sleeve flies and adheres to the electrostatic latent image on the photosensitive member, and the latent image is visualized as a reverse developed toner image. The

  In this jumping development method, the frictionally charged toner is moved onto the photoconductor by the force of the electric field. Therefore, uniform charging of the toner is important for faithfully reproducing the latent image.

  For uniform charging, the uniform shape and particle size of the toner are important factors, and various developments have been made with the aim of improving image quality. However, in order to meet the demand for higher image quality in recent years, the shape and particle diameter of the toner are not limited to be uniform, but the particle diameter is reduced (see Patent Documents 1 and 2) and the shape is rounded (Patent Document 3). 4) has been proposed.

  By using the fine particle toner, the surface area per unit mass is increased, so that the surface charge due to frictional charging is increased, and the average charge amount held on the developer carrier is increased. Therefore, it is possible to improve the reproducibility of fine lines and dots and to reduce scattering, and to improve the image quality.

Further, by increasing the circularity of the magnetic one-component toner, it becomes possible to further increase the average charge amount on the developer carrying member, thereby improving selective developability and improving transferability. High image quality is possible.
Japanese Patent Laid-Open No. 1-112253 JP-A-2-284158 Japanese Patent Laid-Open No. 9-284158 JP-A-9-197714

  However, as the circularity of the magnetic one-component toner increases, the contact area between the toners increases and the average charge amount in frictional charging increases, causing a charge-up phenomenon. At this time, the toner charged up to the normal charge polarity (minus in this case) of the toner is held by the mirror force on the sleeve which is the image carrier, and the toner newly supplied onto the sleeve is difficult to be charged. As a result, the average charge amount of the toner tends to be non-uniform.

Further, when the toner on the developing sleeve is not consumed (for example, after outputting an image with a printing rate of 0 (%)) and the toner on the developing sleeve is consumed (for example, with a printing rate of 100 (%)) Since the difference from the average charge amount after image output becomes large, a difference in density occurs between the first and second rounds of the sleeve, and the image history of the first round of the sleeve remains after the second round (hereinafter this phenomenon). "Sleeve negative ghost").

  As a method of reducing the sleeve negative ghost, there is a solution of removing the toner on the developing sleeve once, for example, attaching a roller in contact with the developing sleeve, but this leads to an increase in cost.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a technique capable of stably obtaining a high-quality image with suppressed generation of ghost at low cost.

In order to achieve the above object, the present invention provides:
A developer container for storing the developer;
A developer carrier that is rotatably provided and carries a developer contained in the developer container;
Developer regulation that adjusts the amount of developer provided for development by regulating the layer thickness of the developer that is provided in contact with the developer carrying body with a free end and is carried on the developer carrying body A member,
In a developing device comprising:
A developer circulation regulating member that has a free end and regulates the circulation of the developer in the developer container;
The developer circulation regulating member is at least upstream of the reference line connecting the rotation center of the developer carrier and the free end of the developer regulating member with respect to the rotation direction of the developer carrier from the reference line. Extending to
Further, the free end of the developer circulation regulating member is a region within 40 degrees from the reference line to the upstream side in the rotation direction of the developer carrier, with the rotation center of the developer carrier as a center. In addition, the distance from the rotation center of the developer carrier is provided in an area that is larger than the size of a line segment connecting the center of the developer carrier and the free end of the developer regulating member within 6.0 mm. It is characterized by being.

  The image forming apparatus according to the present invention includes an image carrier and the developing device described above that performs a developing action on the image carrier.

  The process unit according to the present invention has at least the developing device described above, and is configured to be detachable from the main body of the image forming apparatus.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the technique which can obtain the high quality image which suppressed generation | occurrence | production of a ghost stably at low cost.

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

  Hereinafter, an image forming apparatus according to Embodiment 1 of the present invention will be described.

(overall structure)
The image forming apparatus according to this embodiment is a laser beam printer using an electrophotographic technique in which a process cartridge (process unit) 2 is detachable from an image forming apparatus main body (hereinafter referred to as an apparatus main body) 1.

  Here, an image forming apparatus using electrophotographic technology forms an image on a recording medium using an electrophotographic image forming system. Examples of the electrophotographic image forming apparatus include an electrophotographic copying machine, an electrophotographic printer (for example, a laser beam printer, an LED printer, etc.), a facsimile machine, a word processor, and the like. In this embodiment, the process unit refers to a unit in which at least the developing means is formed into a cartridge and can be attached to and detached from the main body of the electrophotographic image forming apparatus. Further, as shown below, the developing means and the electrophotographic photosensitive member may be integrated into a cartridge.

  When the process cartridge 2 is mounted on the apparatus main body 1, an exposure device (laser scanner unit) 3 is disposed above the process cartridge 2, and a recording medium (sheet) to be image-formed is disposed below the process cartridge 2. Material) A sheet tray 4 containing P is disposed. Further, the image forming apparatus main body 1 includes a pickup roller 5, a paper feed roller (not shown), a conveyance roller (not shown), a transfer guide 6, a transfer charging roller 7, along the conveyance direction of the sheet material P. A conveyance guide 8, a fixing device 9, a paper discharge roller 10, a paper discharge tray 11, and the like are arranged.

(Process cartridge configuration)
The process cartridge 2 integrally accommodates four types of process devices including a photosensitive drum (photosensitive member) 20 as an image carrier, a charging device 30, a developing device 40, and a cleaning device 50. The photosensitive drum 20 and the charging device 30 are attached to a frame 51 of the cleaning device 50. On the other hand, the developing device 40 has coupling arms 48 in the vicinity of both ends thereof.

  The developing device 40 is rotatably attached to the frame 51 by means (not shown) at the tip end region of the coupling arm 48. Further, an urging means 60 that is a coil spring is disposed between the developing device 40 and the frame 51, and the developing device 40 is urged clockwise in the drawing.

  Here, in the developing device 40, a spacing member (not shown) is attached to both ends of a developing sleeve (developing roller) 41 as a developer carrier, and the developing sleeve 41 is developed at a predetermined interval from the photosensitive drum 20. It is held in the device 40.

(Description of image forming process)
Next, an outline of image formation will be described. Based on the print start signal, the photosensitive drum 20 is rotationally driven at a peripheral speed (process speed) of 120.0 mm / s in the arrow R1 direction. A charging device 30 to which a bias voltage is applied is in contact with the outer peripheral surface of the photosensitive drum 20, and the outer peripheral surface of the photosensitive drum 20 is uniformly and uniformly charged negatively in this embodiment by the charging device 30. .

  The laser scanner unit 3 outputs laser light L modulated in accordance with the time-series electric digital pixel signal of the target image information, and enters the process cartridge 2 from the exposure window 53 on the upper surface of the process cartridge 2. Then, the outer peripheral surface of the photosensitive drum 20 is scanned and exposed. As a result, an electrostatic latent image corresponding to the target image information is formed on the outer peripheral surface of the photosensitive drum 20. This electrostatic latent image is subjected to toner by a developer (toner) T on a developing sleeve 41 as a developer carrying member, which has been subjected to tribo application and layer thickness regulation by a developing blade 42 as a developer regulating member of the developing device 40. Developed as an image.

On the other hand, the sheet material P is fed from the sheet tray 4 by the pickup roller 5, the paper feed roller (not shown), and the conveying roller pair (not shown) in synchronization with the output timing of the laser beam L, and the transfer guide 6 is moved. Then, timing is supplied to the transfer position between the photosensitive drum 20 and the transfer charging roller 7. At this transfer position, the toner image is sequentially transferred from the photosensitive drum 20 to the sheet material P.

  The sheet material P to which the toner image has been transferred is separated from the photosensitive drum 20 and conveyed along the conveyance guide 8 to the fixing device 9, and at the nip portion between the fixing roller 9 a and the pressure roller 9 b constituting the fixing device 9. The toner image is fixed to the sheet material P by pressure and heat fixing processing. The sheet material P that has undergone the toner image fixing process is conveyed to the paper discharge roller 10 and discharged onto the paper discharge tray 11.

  On the other hand, after the transfer, the remaining toner on the outer peripheral surface of the photosensitive drum 20 is removed by the cleaning blade 52 of the cleaning device 50, and the photosensitive drum 20 is again subjected to image formation starting from charging.

(Configuration of developing device)
The magnetic one-component toner T (average particle diameter of 7.0 μm) in the toner chamber 45 serving as a developer storage chamber is agitated with the toner, and passes through the toner supply opening 45a serving as an opening provided in the toner chamber 45, thereby supplying the developer supply chamber 44. It is conveyed to. Here, the toner chamber 45 and the developer supply chamber 44 constitute a developing container, and the toner supply opening 45 a is a communication port that connects the toner chamber 45 and the developer supply chamber 44.

The toner T conveyed to the developer supply chamber 44 is attracted to the developing sleeve 41 by the magnet 41a included in the developing sleeve 41, and conveyed toward the developing blade 42 as the developing sleeve 41 rotates in the R2 direction. The developing blade 42 is fed in the direction of the photosensitive drum 20 by applying tribo and layer thickness regulation. Here, in this embodiment, since the normal charging polarity of the toner T is negative, the toner is given a negative tribo by the developing blade 42.

In this embodiment, a magnetic one-component toner T having an average circularity of 0.965 is used. The average circularity of the magnetic one-component toner T in this embodiment is used as an index for quantitatively expressing the shape of the particles, and the flow type particle image analyzer “FPIA-1000” manufactured by Toa Medical Electronics is used. The circularity (ai) of the measured particle is obtained by the following formula (I), and the value obtained by dividing the total circularity of all the measured particles by the total number of particles (m) is defined as the circularity. To do.

Circularity (ai) = L0 / L Formula (I)
(In the formula, L0 represents the perimeter of a circle having the same projected area as the magnetic toner particle image, and L represents the perimeter of the projected image of magnetic toner particles.)

  Further, as the developing sleeve 41 in this embodiment, an aluminum base tube is sandblasted and roughened, and then coated with a phenol resin in which carbon black fine particles and graphite fine particles are dispersed, and the surface roughness Ra = 1.0 μm. The charge-up phenomenon of the toner T is suppressed by using the above. The developing blade 42 is formed by adhering urethane rubber to a support metal plate, and abuts against the developing sleeve 41 at a pulling pressure of 20 g / cm in a direction against the rotation of the developing sleeve (counter direction).

Here, a developing bias in which an alternating voltage (peak-to-peak voltage = 1600 Vpp, frequency f = 2400 Hz) is superimposed on a direct-current voltage (Vdc = −400 V) is applied to the developing sleeve 41, and the photosensitive drum 20 is grounded. Since an electric field is generated in a region where the photosensitive drum 20 and the developing sleeve 41 face each other, the latent image on the surface of the photosensitive drum 20 is reversely developed by the negatively charged toner T described above.

  In this embodiment, the electrostatic latent image formed on the outer peripheral surface of the photosensitive member corresponding to the target image information is subjected to charge application and layer thickness regulation by the developer regulating member (developing blade 42) of the developing device 40. Regulation of toner circulation when toner is sent from the toner storage portion to the developing sleeve in a series of image forming processes until the toner image is developed by the developer (toner) on the received developer carrying member (developing sleeve 41) This relates to the member.

  Subsequently, the toner circulation regulating member (developer circulation regulating member) according to the present embodiment will be described in detail.

(Explanation of developer circulation regulating member)
When the toner carried on the developing sleeve 41 is regulated by the developer regulating member (developing blade 42), the toner receives frictional charge and holds the charge on the toner surface. Therefore, if the toner on the developing sleeve 41 is not consumed by printing, it remains on the developing sleeve 41 and is repeatedly frictionally charged by the developing blade 42.

  At this time, if the toner on the developing sleeve 41 is not consumed, the same toner is only held on the developing sleeve 41, but the toner on the developing sleeve 41 is consumed by printing (particularly when the printing rate is 100%). In this case, when fresh toner that has not been subjected to frictional charging is supplied from the developing container, the average charge amount differs between the first and second rounds of the developing sleeve. In the jumping development method, the difference in the average charged charge amount of the toner on the developing sleeve causes a problem that the developability, that is, the image density differs.

  Therefore, it is necessary to prevent the fresh toner from the developing container from being provided directly on the developing sleeve 41. However, the toner circulation around the magnetic force S2 of the normal magnet roll is accompanied by the developing sleeve 41 and moves from the bottom to the top as indicated by the arrow A in FIG. Therefore, the fresh toner from the stirring member 43 cannot be prevented, and a difference in the average charge amount on the developing sleeve between when the toner is consumed and when the toner is not consumed is generated, and sleeve negative ghost is generated. In addition, when the circularity of the toner is 0.96 or more, since the average charge amount due to frictional charging is large, sleeve negative ghost is remarkably generated.

Here, Table 1 shows the relationship between the average circularity of the magnetic one-component toner T and the toner coat layer on the developing sleeve 41 in the conventional developing device configuration.

From Table 1, the toner coat weight W (mg / cm ² ) does not depend on the average circularity of the toner T, and the toner coat weight W ₀ (mg / cm ² ) after image output with a print rate of 0 (%) and the print rate A similar difference is seen with the toner coat weight W ₁₀₀ (mg / cm ² ) after 100% image output. However, the toner average charge amount Q / M (μc / g) increases as the average circularity of the toner T increases, and the toner average charge amount Q / M ₀ (μC / g) after image output with a printing rate of 0 (%) increases. Thus, the difference from the average toner charge Q / M ₁₀₀ (μC / g) after image output with a printing rate of 100 (%) is large. This shows that the sleeve negative ghost becomes worse as the average circularity increases.

  Accordingly, as a solution to the sleeve negative ghost, as a solution to the sleeve negative ghost, the developer circulation regulating member 70 is disposed in the vicinity of the developing blade 42 as shown in FIG. 6 to circulate the toner T from (A) to (B It has been found that it is effective to make a smaller circulation behind the developing sleeve as shown in FIG. This is because the developer circulation regulating member 70 is disposed between the developing sleeve 41 and the toner supply opening 45a, so that the toner circulation that prevents the fresh toner from being fed by the stirring member 43 (arrow C in FIG. 6) occurs. It is. Therefore, it is possible to reduce the difference in the average charge amount on the developing sleeve 41 between when the toner on the developing sleeve 41 is consumed and when it is not.

(Verification experiment 1)
Hereinafter, a verification experiment in which the difference between the sleeve negative ghost in the case where the developer circulation regulating member 70 is provided and the case where the developer circulation restriction member 70 is not provided will be described.

  This verification experiment was performed in an environment of a temperature of 23 ° C. and a humidity of 50%, and the results at that time are shown in Table 2. In this embodiment, the material of the developer circulation regulating member 70 is molded and is not particularly limited to this embodiment as long as it is a non-magnetic material. Further, in this embodiment, the developer circulation regulating member 70 has a thickness of 1.5 mm and a vertical length of 11.0 mm, and is disposed at the upper part of the developing container, and is disposed substantially vertically so as to go downward from the upper part. ing.

  In particular, the relationship between the tip position M of the free end of the developing blade 42 and the tip position P of the free end of the developer circulation regulating member 70 is important for the sleeve negative ghost, and the center of the developing sleeve 41 that is the developer carrying member. (Rotation center, axis) In a straight line drawn from O to points M and P, when OM = α, OP = r, the angle θ formed by a straight line passing through OM (reference line) and a straight line passing through OP (see FIG. 1) The condition is that the tip position of the developer circulation regulating member 70 is close to the tip position of the developing blade 42 and as long as possible in the vertical direction. In this verification experiment, r−α = 1.6 mm and θ = 11.5 °. The tip position of the developer circulation regulating member 46 may be provided so as to extend at least to the reference line (a straight line passing through the OM) from the downstream side in the rotation direction of the developing sleeve 41 toward the upstream side. The developer circulation regulating member 46 may be disposed at least over the developer application area in the longitudinal direction of the developing sleeve 41.

The toner used in this verification experiment has an average circularity of 0.965, and the toner average charge amount Q / M (μC / g) is a value measured by a suction type Faraday cage method. The toner T on the developing sleeve 41 is sucked by a suction pump and collected by a Faraday cage. A value obtained by calculation from the collected toner amount and its charge amount is a toner average charge amount Q / M (μC / g). In addition, the case where a sleeve negative ghost occurs is indicated as x, the case where a sleeve negative ghost occurs is indicated as Δ, and the case where no sleeve negative ghost occurs is indicated as ◯. According to Table 2, by arranging the developer circulation regulating member, the toner average charge amount becomes the same when the printing rate is 0% and when the printing rate is 100%, and the sleeve negative ghost is improved. I can confirm.

(Developer circulation regulating member and fading)
However, in order to obtain an effect of countermeasures against the sleeve negative ghost, an attempt is made to dispose the tip position P of the developer circulation regulating member 70 near the tip position M of the developing blade 42 and as long as possible in the vertical direction. Therefore, the toner supply from the toner chamber 45 to the developing sleeve 41 by the stirring member 43 is hindered.

  Therefore, there is a concern that a problem such as image omission due to insufficient toner supply (hereinafter, this phenomenon is referred to as “fading”) may occur as an adverse effect when a high-print pattern is continuously fed. For the above reason, it is necessary to consider the position where both the sleeve negative ghost and the fading are compatible when the developer circulation regulating member is provided.

  Particularly, r-α and θ indicating the tip position of the developer circulation regulating member 70 are important, and Table 3 shows the relationship between the sleeve negative ghost and the fading when r-α and θ have respective values. . In Table 3, the same experimental conditions as in the verification experiment 1 are used. In addition, the case where fading occurs is indicated as x, the case where slight fading occurs, and the case where it does not occur are indicated as ◯.

  From Table 3, it can be seen that the larger θ is, the more effective the sleeve negative ghost is, but the fading tends to deteriorate. Further, the smaller r-α is, the more effective the sleeve negative ghost is. However, there is a tendency for the fading to deteriorate similarly.

From the above, the positional relationship between r-α and θ has the opposite effect to the sleeve negative ghost and fading, so the developer circulation regulating member 70 must be disposed at the compatible position. . Therefore, when r-α is 0 to 6.0 mm, preferably 0.5 to 3.0 mm, and θ is 0 to 40 °, preferably 5.0 to 30 °, both sleeve negative ghost and fading can be achieved. It becomes possible.

(Developer circulation regulating member in a small developing device)
Further, in a small-sized developing device 40 having a relatively small developing sleeve 41 and a small toner chamber 45, if the circulation of the toner T is reduced, the toner in the developer supply chamber 44 and the toner chamber 45 cannot be exchanged well. There is a concern that harmful effects such as thinness will occur.

  Here, the small developing device 40 is defined as that the outer diameter of the developing sleeve 41 is 15 mm or less and the distance from the center O of the developing sleeve 41 to the opening 45 a of the toner chamber 45 is 20 mm or less. In this embodiment, the outer diameter of the developing sleeve 41 is 14 mm, and the distance from the center of the developing sleeve 41 to the toner supply opening 45a is 16 mm.

  In order to improve the above adverse effects when the developing device 40 is small, the thickness of the developer circulation regulating member 70 and the distance between the toner supply opening 45a and the developer circulation regulating member 70 become important. First, the thickness Lw of the developer circulation regulating member 70 will be described.

When Lw became small, the sleeve negative ghost deteriorated. This is because the effect of changing the toner circulation by the developer circulation regulating member 70 becomes smaller as the thickness becomes thinner. For this reason, the developer circulation regulating member 70 cannot create a circulation like the toner circulation B shown in FIG. 6, and the result is the same as the case where the developer circulation regulating member 70 is not provided. Here, the thickness Lw at this time is the width PQ (see FIG. 1) at the lowermost end of the developer circulation regulating member 70, and there is no particular limitation as long as the width and shape are higher than PQ. Therefore, there is a lower limit value for Lw from the viewpoint of sleeve negative ghost.

  Further, when Lw becomes large, there is a limit to the maximum thickness of the developer circulation regulating member 70 at this time. When the developing device 40 is small, if the upper portion of the toner chamber 45 is completely filled and the height in the toner chamber 45 is lowered to reduce the volume, a problem such as low density may occur. This is because, since the toner circulation is reduced, it becomes difficult for the toner in the toner chamber 45 to be replaced, and the toner is excessively fed by the stirring member 43, thereby causing packing and toner deterioration.

  For this reason, when the developing device 40 is small, a certain amount of space exists above the toner chamber 45, and if the toner escape space is not secured to some extent, a bad effect is caused. Therefore, there is a maximum value for the thickness of the developer circulation regulating member 70. At this time, the range of the thickness of the developer circulation regulating member 70 is the thickness Lw of the developer circulation regulating member 70 in the cross section in the short direction of the process cartridge, and the distance a between the developer circulation regulating member 70 and the toner supply opening 45a. It depends on the size relationship. For this reason, when Lw and a are determined so as to satisfy the following formula (II), even if the developer circulation regulating member 70 is provided, the sleeve negative ghost can be improved without causing any harmful effects. .

Lw / a <0.7 (1.2 ≦ Lw) (II)
(Verification experiment 2)
Tables 4 and 5 show the relationship between Lw, a, sleeve negative ghost, and density thinness when the developer circulation regulating member 70 is disposed so as to satisfy the formula (II). At this time, r−α = 1.6 mm and θ = 11.5 °. The conditions of the verification experiment 2 are the same as those of the verification experiment 1. Further, regarding the low density, an image having a printing rate of 2.0% was used, and the determination was made based on the density of solid black after passing 1,000 sheets. The density at this time was measured using a reflection density ratio measuring device (Macbeth densitometer RD-918). When it is 1.0 or less, it is set as x.

  From Table 4, it can be seen that the size of Lw in this embodiment is required to be 1.2 mm or more from the viewpoint of sleeve negative ghost. Further, from Table 5, it is possible to obtain a good image free from the negative effects of the sleeve negative ghost when the expression (II) is satisfied. From the above, it is possible to improve the sleeve negative ghost by disposing the developer circulation regulating member.

  In the first embodiment, it is possible to improve the sleeve negative ghost by providing the developer circulation regulating member. Therefore, the second embodiment is characterized in that the developer circulation regulating member not only improves the sleeve negative ghost, but also serves as a sequential detection of the remaining amount of toner in a capacitance detection type. In other words, the laser beam printer of this embodiment includes a developer remaining amount detecting unit capable of sequentially detecting the remaining amount as the toner is consumed.

  FIG. 7 is a partial cross-sectional view of the developing device according to this embodiment. The image forming apparatus according to the present embodiment has the same configuration as the image forming apparatus according to the above-described embodiment, and the same components are denoted by the same reference numerals and description thereof is omitted.

  The plate antenna PA shown in FIG. 7 also functions as the developer circulation regulating member 70 described in the first embodiment. The toner T in the toner chamber 45 is fluid and the degree of decrease in the toner T can be directly recognized. Such a developing device 40 is installed.

  In this embodiment, the plate antenna PA is formed by using a sheet metal made of stainless steel (SUS316) having a thickness of 0.3 mm in an L shape so that the degree of decrease of the toner T in the toner chamber 45 can be seen. The remaining amount of toner existing between the developing sleeve 41 and the plate antenna PA can be detected.

  Further, the installation location of the plate antenna is adjusted so that the output when the toner T is full is 1V, and the output when the toner T is empty is 3V. Further, adjustment is made so that the relationship between the decrease in the toner amount and the detection output changes almost linearly. Finally, r−α = 1.6 mm and θ = 11.5 ° were set as the tip positions of the plate antenna PA (developer circulation regulating member) in the present embodiment.

  Any material may be used for the plate antenna PA as long as it is a plate having good conductivity. However, a material that does not adversely affect the toner particles and is resistant to environmental conditions such as humidity is desired. And the shape which can energize from the outside is formed in the at least one side of plate antenna PA. This connectable portion may be directly connected by a conducting wire or the like, or may be skewered with a conductive pin shape from the side of the cartridge. In this embodiment, a pin-shaped object is inserted into the raising portion (not shown) through the cartridge side wall.

  Further, the remaining toner amount detection by the developing sleeve 41 and the plate antenna PA measures the remaining toner amount using a developing bias applied to the developing sleeve 41. Specifically, the voltage value induced in the plate antenna PA by the developing bias applied to the developing sleeve 41 is read.

  At this time, if the dielectric constant varies depending on the amount of toner remaining between the developing sleeve 41 and the plate antenna PA, the voltage value induced in the plate antenna PA also varies. The remaining toner level is detected by looking at the different voltage values.

The apparatus main body and the cartridge are provided with electrical contacts (not shown), and when the cartridge is mounted in the apparatus main body, the plate antenna PA of the cartridge and the remaining toner level detection detection unit ( (Not shown) are electrically connected.

  A measurement value generated with respect to the capacitance between the developing sleeve 41 and the plate antenna PA, that is, a voltage value is converted into a digital value, and the result of detecting the remaining toner level is compared with the remaining amount threshold value table. Outputs to the central processing unit (CPU) (not shown) built in the printer in the form of display and printable number of sheets, and outputs remaining toner percentage information and printable number of sheets information to the controller unit as necessary To do.

  Then, the remaining amount% of toner and the number of printable sheets are provided to the operation panel built in the personal computer or printer connected to the controller unit, and provided to the user by the display device.

  This controller unit is mainly located between the personal computer and the printer, and performs drawing by operating an output device such as a photosensitive drum or a semiconductor laser based on image information transmitted from the personal computer. In addition, warnings and the like issued from each part of the printer main body are collected via a controller unit and transmitted to a display device such as a personal computer or an operation panel to be notified to the user. In recent years, the controller unit is built in the printer.

(Verification experiment)
In order to confirm whether the remaining toner amount can be detected while satisfying both the sleeve negative ghost and the fading under the above conditions, the remaining toner amount detection output value was confirmed.

  The bias was applied to the developing sleeve 41 at a frequency of 23 ° C. and a humidity of 50%. The frequency applied was 2.4 kHz, the AC peak-to-peak voltage was 1500 Vpp, and the DC voltage was −400 V. The toner has an average circularity of 0.965, and the initial toner weight is 300 g. Further, the remaining amount of toner was detected by continuous paper passing using an image having a printing rate of 4.0% as the paper passing pattern. FIG. 8 shows the output value and the remaining amount of toner at that time.

  In FIG. 8, the voltage changes from the remaining amount of toner of about 30%. This is detected only when the remaining amount of toner is actually 30% or less because the detectable remaining amount of toner is only near the developing sleeve. This is because it is possible.

  As described above, the plate antenna PA according to the present embodiment can have a function of detecting the remaining amount of electrostatic capacity toner while also serving as a developer circulation regulating member.

1 is a partial cross-sectional view of a developing device according to Embodiment 1. FIG. 1 is a longitudinal sectional view of an image forming apparatus according to Embodiment 1. FIG. 1 is a longitudinal sectional view of a developing device according to Embodiment 1. FIG. 3 is a longitudinal sectional view of a process cartridge according to Embodiment 1. FIG. FIG. 3 is a schematic diagram of toner circulation on the back of the developing sleeve in Embodiment 1. 6 is a schematic diagram of toner circulation on the back of the developing sleeve when the developer circulation regulating member in Embodiment 1 is provided. FIG. 6 is a partial cross-sectional view of a developing device according to Embodiment 2. FIG. 3 is a toner remaining amount detection value in Embodiment 2.

Explanation of symbols

1. Image forming device body (device body)
2 Process cartridge 3 Exposure device (laser scanner unit)
4 Sheet tray 5 Pickup roller 6 Transfer guide 7 Transfer charging roller 8 Transport guide 9 Fixing device 10 Paper discharge roller 11 Paper discharge tray 20 Photosensitive drum 30 Charging device 40 Developing device 41 Developing sleeve (developer carrier)
41a Magnet roll 42 Developing blade (developer regulating member)
43 stirring member 44 developer supply chamber 45 toner chamber 45a toner supply opening 46 developer circulation regulating member 48 coupling arm 50 cleaning device 51 frame 52 cleaning blade 60 coil spring 70 developer circulation regulating member L laser beam P recording medium (sheet material) )
T Developer (toner)
PA plate antenna

Claims (12)

A developer container for storing the developer;
A developer carrier that is rotatably provided and carries a developer contained in the developer container;
Developer regulation that adjusts the amount of developer provided for development by regulating the layer thickness of the developer that is provided in contact with the developer carrying body with a free end and is carried on the developer carrying body A member,
In a developing device comprising:
A developer circulation regulating member that has a free end and regulates the circulation of the developer in the developer container;
The developer circulation regulating member is at least upstream of the reference line connecting the rotation center of the developer carrier and the free end of the developer regulating member with respect to the rotation direction of the developer carrier from the reference line. Extending to
Further, the free end of the developer circulation regulating member is a region within 40 degrees from the reference line to the upstream side in the rotation direction of the developer carrier, with the rotation center of the developer carrier as a center. In addition, the distance from the rotation center of the developer carrier is provided in an area that is larger than the size of a line segment connecting the center of the developer carrier and the free end of the developer regulating member within 6.0 mm. A developing device.   The developing device according to claim 1, wherein the developer circulation regulating member is disposed over at least a developer application area in a longitudinal direction of the developer carrier.   The developer circulation regulating member is disposed on an upper part of the developer container, and is provided to extend from the upper part of the developer container to the free end of the developer circulation regulating member. The developing device according to claim 1 or 2.   The developing device according to claim 1, wherein the developer carrying member has an outer diameter of 15 mm or less.   The developing device according to claim 1, wherein the developer stored in the developing container has a circularity of 0.96 or more.   The developing device according to claim 1, wherein a thickness of the free end of the developer circulation regulating member is 1.2 mm or more. An opening provided in the developer container for allowing the developer housed in the developer container to move to the developer carrier;
When the thickness of the free end of the developer circulation regulating member is Lw, the distance a between the developer circulation regulating member and the opening is:
Lw / a <0.7 (1.2 ≦ Lw)
The developing device according to claim 1, wherein:   The developing device according to claim 7, wherein a distance between the rotation center of the developer carrying member and the opening is 20 mm or less. The developer circulation regulating member is composed of a conductive member,
6. The remaining amount of developer is detected based on a voltage induced in the developer circulation regulating member when a developing bias is applied to the developer carrying member. The developing device according to 1.   An image forming apparatus comprising: an image bearing member; and the developing device according to claim 1 that performs a developing action on the image bearing member.   A process unit comprising at least the developing device according to claim 1 and configured to be detachable from an image forming apparatus main body.   12. The process unit according to claim 11, wherein the process unit includes an image carrier on which a developing action is performed by the developing device.

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