JP2009210721A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a developing device where a supply amount of a toner supplied from a toner storage chamber to a developing chamber is stable regardless of an amount of the toner in the toner storage chamber, and an image forming apparatus. <P>SOLUTION: A pitch of a blade 168A of a spiral blade 168 of a dispense auger 160 is narrowed stepwise as going toward a downstream side from an upstream side in a conveying direction of the toner T, whereby a feed amount of the toner T at each rotation of the blade 168A is reduced to make a compression force of the toner T stronger stepwise. Thus, even if a cavity of the toner T is formed at the upstream side in the conveying direction of the toner T due to the reduction of the amount of the toner T in the toner storage chamber 150 in the dispense auger 160, the cavity is reduced on the downstream side in the conveying direction, and the supply amount of the toner is made stable regardless of the amount of the toner T in the toner storage chamber 150. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a developing device and an image forming apparatus.

  In general, when a two-component developer containing toner and carrier is used, the balance between toner consumption and toner supply is controlled so that the ratio of toner and carrier falls within a desired range.

  For example, when the ratio of the toner in the two-component developer is decreased, the charge amount of the toner is increased, the development amount is decreased, and the image density is decreased. If the image density becomes too low, the carrier is developed, and the photoreceptor is damaged, causing a problem. Conversely, as the toner ratio increases, the toner charge amount decreases, the development amount increases, and the image density increases. In addition, there is a problem of becoming a cloud and contaminating the inside of the apparatus.

Here, in order to keep the toner density constant,
There is a method of controlling the toner supply means based on (1) toner consumption calculated based on image information and (2) toner density detection result.
As a method for detecting the toner density in (2),
(2-1) a method of detecting the magnetic permeability of the developer in the developing device with a magnetic permeability sensor;
(2-2) There is a method of creating a test patch and detecting the density of the test patch with an optical sensor.

  As described above, when the toner density is controlled within the predetermined range by controlling the toner supply means, the toner density actually changes within the predetermined range. Therefore, a test patch is created, and the toner density is measured by the optical sensor. Therefore, it is necessary to adjust the exposure amount of writing and the developing bias to control the image density to be constant.

  However, in the case of (2), it takes time because the toner is agitated by the carrier after toner supply and changes are detected. Particularly in (2-2), since a test patch cannot be formed during printing, it cannot be detected in real time.

  On the other hand, in the case of (1), since the remaining amount of toner in the toner storage chamber is predicted from the driving time of the toner supply means, it is important that the toner supply amount is stable regardless of the amount of toner in the toner storage chamber. Become.

  For example, if the toner is directly supplied from the toner storage chamber to the developing chamber, the amount of toner supply increases when there is sufficient fluctuation in the rotation frequency of the stirring member in the toner storage chamber or when there is sufficient toner in the toner storage chamber. When the amount of toner decreases, the amount of toner supply also decreases. Therefore, a method is adopted in which an auger for toner conveyance is provided between the toner storage chamber and the developing chamber, and the driving of the auger is controlled.

  For example, Patent Document 1 proposes an apparatus that shortens the toner supply path from the toner storage chamber to the developing chamber and supplies toner directly from the toner storage chamber to the toner supply path in order to reduce the size.

Further, in Patent Document 2, in a plurality of augers disposed in a developing device, the shape of each auger is changed to increase the frictional charge between the toner and the carrier, thereby increasing the charge amount of the toner. .
JP 2006-267722 A JP 09-120200 A

  In view of the above facts, an object of the present invention is to provide a developing device and an image forming apparatus in which the amount of toner supplied from the toner containing chamber to the developing chamber is stable regardless of the amount of toner in the toner containing chamber. To do.

  According to the first aspect of the present invention, in the developing device, a toner storage chamber in which toner is stored, a development chamber in which a developer containing toner and a magnetic carrier is held by a developer holder, the toner storage chamber, and the development Connect the chambers and agitate the toner supplied from the toner storage chamber side, and gradually or stepwise increase the toner compression force as it goes from the upstream side to the downstream side in the toner transport direction. And a toner supply means.

  According to a second aspect of the present invention, in the developing device according to the first aspect, the toner supply unit is provided so as to be rotatable in the toner supply passage, a toner supply passage connecting the toner storage chamber and the development chamber, and the toner supply passage. And a blade member formed in a spiral shape around the rotation shaft, and the pitch of the blade portion of the blade member goes from the upstream side to the downstream side in the toner conveyance direction. According to the above, it is narrowed gradually or stepwise.

  According to a third aspect of the present invention, in the developing device according to the first or second aspect, the toner supply unit is rotatable within the toner supply passage, a toner supply passage connecting the toner storage chamber and the development chamber, and the toner supply passage. And a blade member spirally formed around the rotation shaft, and the thickness of the blade portion of the blade member is changed from the upstream side to the downstream side in the toner conveyance direction. As it goes to, it becomes thicker gradually or stepwise.

  According to a fourth aspect of the present invention, in the developing device according to any one of the first to third aspects, the toner supply means includes a toner supply passage connecting the toner storage chamber and the development chamber, and the toner supply. A rotation shaft provided rotatably in the passage, and a blade member formed in a spiral shape around the rotation shaft, wherein the outer diameter of the rotation shaft is upstream in the toner conveyance direction. It is characterized by increasing gradually or stepwise from the downstream to the downstream side.

  According to a fifth aspect of the present invention, in the developing device according to any one of the first to fourth aspects, the toner supply means includes a toner supply passage connecting the toner storage chamber and the development chamber, and the toner supply. A rotation shaft provided rotatably in the passage, and a blade member formed in a spiral shape around the rotation shaft, and includes a cross-sectional area of the toner supply passage and a blade portion of the blade member. The outer diameter decreases gradually or stepwise from the upstream side to the downstream side in the toner conveyance direction.

  According to a sixth aspect of the present invention, in the developing device according to any one of the second to fifth aspects, the supply port through which the toner is supplied from the toner storage chamber to the wall portion configuring the toner supply passage. A discharge port for discharging the toner conveyed through the toner supply passage to the developing chamber, and the toner storage chamber and the toner supply to the wall portion located between the supply port and the discharge port. A through hole for connecting the passages is provided.

  According to a seventh aspect of the present invention, in the developing device according to the sixth aspect, the through hole is provided at a position including a changing point of the compressive force of the toner.

  According to an eighth aspect of the present invention, in the image forming apparatus, the image holding member on which an electrostatic latent image is formed on the surface, and the toner image is manifested on the image holding member. And a developing device according to the item.

  According to the first aspect of the present invention, the gap can be reduced on the downstream side in the transport direction, and the toner supply amount can be stabilized regardless of the amount of toner in the toner storage chamber.

  According to the second aspect of the present invention, by reducing the pitch of the blade portions of the blade member, the toner feed amount per one rotation of the blade portion is reduced, so that the toner is compressed.

  According to the third aspect of the present invention, when the outer diameter of the rotating shaft is increased, the volume for transporting the toner is reduced, so that the toner is compressed.

  According to the fourth aspect of the present invention, when the thickness of the blade portion of the blade member is increased, the volume for transporting the toner is reduced, so that the toner is compressed.

  According to the fifth aspect of the present invention, by reducing the cross-sectional area of the toner supply passage and the outer diameter of the blade portion of the blade member, the volume for conveying the toner is reduced, so that the toner is compressed.

  According to the sixth aspect of the present invention, when the toner supply is excessive, the developer in the toner supply passage is pushed out to the toner storage chamber through the through hole, and the toner in the toner supply passage is not excessively compressed. Like that.

  According to the seventh aspect of the present invention, by providing the through hole at a position including the change point of the toner compression force, the toner in the toner supply passage can be more effectively pushed into the toner storage chamber. .

  According to the invention described in claim 8, it is possible to obtain substantially the same effect as the effect described in any one of claims 1-7.

An image forming apparatus provided with a developing device according to an embodiment of the present invention will be described.
(Image forming device)
First, the image forming apparatus will be described. As shown in FIG. 1, in the image forming apparatus 10, process cartridges 14 of four colors (in this embodiment, yellow, magenta, cyan, and black) are arranged in the vertical direction. The process cartridge 14 includes a photoconductor cartridge 62 having a photoconductor 16 and a developing device 64 (details will be described later).

  The photoreceptor cartridge 62 is disposed in the lateral direction of the photoreceptor (image holding body) 16, the cleaning device 22 disposed around the photoreceptor 16, the charging roll 18, the erase lamp 24, and the cleaning device 22. And a sub-toner supply unit 66.

  The sub-toner replenishment unit 66 is provided with a pair of support protrusions 78 extending in a direction orthogonal to the axial direction of the photoconductor 16. By inserting the support protrusion 78 into a cartridge receiving portion (not shown) of the image forming apparatus 10, the process cartridge 14 is mounted on the image forming apparatus 10.

  In addition, a sheet feeding cassette 26 in which the sheet material P is stored is provided in the lower part of the image forming apparatus 10, and a pickup roll 28 that feeds the sheet material P at a predetermined timing is provided in the vicinity of the sheet feeding cassette 26. Is provided. The sheet material P sent out from the paper feed cassette 26 by the pickup roll 28 is sent out to the paper transport path 34 via the transport roll 30 and the registration roll 32 and transported to a transport device 48 described later.

  On the other hand, the process cartridge 14 is arranged in the order of yellow, magenta, cyan, and black from the upstream side of the paper transport path 34. Scanning light is applied to the process cartridge 14 on the side of the process cartridge 14. An exposure device 36 for irradiating is disposed.

  In the exposure device 36, a semiconductor laser (not shown), a polygon mirror 40, an imaging lens 44, and a mirror 46 are disposed in a housing 38, and light from the semiconductor laser is deflected and scanned by the polygon mirror 40. The photosensitive member 16 is irradiated through the imaging lens 44 and the mirror 46. Thereby, an electrostatic latent image corresponding to the image information is formed on the photosensitive member 16.

  A transport device 48 is disposed at a position facing the photoconductor 16 across the paper transport path 34. The conveying device 48 includes a pair of stretching rolls 51 and 52 provided along the side wall 10 </ b> A of the image forming apparatus 10, and a conveying belt 53 wound around the stretching rolls 51 and 52. The tension roll 52 is rotated by a motor (not shown) so that the transport belt 53 moves.

  An adsorption roll 55 is disposed in the vicinity of the tension roll 51, and the sheet material P is electrostatically adsorbed to the conveyance belt 53 by applying a voltage to the adsorption roll 55. ing.

In addition, transfer rolls 54 are disposed on the back surface of the conveyor belt 53 at positions facing the photoconductors 16 of the respective colors. A toner image, which will be described later, on the photoreceptor 16 is transferred onto the sheet material P conveyed by the conveying belt 53 by the transfer roll 54 and fixed by the fixing device 56. Then, the sheet material P on which the toner image is fixed is discharged to the discharge tray 60 by the discharge roll 58.
(Developer)
Next, a first embodiment of the developing device according to this embodiment will be described.
(First embodiment)
As shown in FIG. 2, the developing device 64 is a developing unit 68 that faces the photoreceptor 16 and visualizes the electrostatic latent image on the photoreceptor 16 with a two-component developer G composed of toner T and a magnetic carrier. The main toner supply unit 70 supplies toner T to the developing unit 68.
(Development unit)
The developing unit 68 has a housing 80. The housing 80 is provided below the photoconductor 16 and has an opening 82 that opens toward the photoconductor 16. In addition, a developer storage chamber (development chamber) 84 is formed in the housing 80, and the developer storage chamber 84 can store a developer G composed of toner T and a magnetic carrier. .

  Further, a developing roll 86 as a developer holder is provided in the housing 80 so as to be partially exposed from the opening 82 of the housing 80, and the developing roll 86 is rotatably supported by the housing 80. Has been. A gear (not shown) is fixed to the end of the developing roll 86, and the rotational force from the motor is transmitted to the gear so that the developing roll 86 is rotated via the gear.

  Further, the developing roll 86 includes a thin cylindrical sleeve 86A having conductivity that is rotatable, and a fixed columnar magnet roll 86B.

  Further, a cylindrical developer regulating roll 50 as a developer regulating member that regulates the amount of the developer G on the developing roll 86 is fixedly disposed with a gap S so as to face the sleeve 86A.

  Thereby, the developing roll 86 adsorbs the magnetic carrier contained in the developer G by magnetic force, forms a magnetic brush of the developer G on the surface, and the amount of the developer G is regulated by the developer regulating roll 50. The developer G is conveyed to a position facing the photoconductor 16. Then, the electrostatic latent image formed on the photoreceptor 16 is visualized as a toner image by the developer G on the developing roll 86.

  Below the developing roll 86, stirring and transporting augers 88 and 89 that transport the developer G along the axial direction of the developing roll 86 are disposed. As shown in FIG. 3, the agitating / conveying augers 88 and 89 include rotation shafts 88 </ b> A and 89 </ b> A, respectively, and are rotatably supported on the peripheral wall of the housing 80. Further, spiral blades 88B and 89B are spirally wound around the rotating shafts 88A and 89A of the agitating and conveying augers 88 and 89 at a predetermined pitch.

  Further, gears (not shown) are fixed to the end portions of the rotary shafts 88A and 89A, respectively, and a rotational force from a motor (not shown) is transmitted to the gears, and the agitating and conveying augers 88 and 89 rotate through the gears. .

  A partition wall 90 is formed between the agitating / conveying auger 88 and the agitating / conveying auger 89, and the partition wall 90 allows an area (first agitating path) in which the agitating / conveying auger 88 is disposed in the developer storage chamber 84. ) 92 and an area (second agitation path) 93 in which the agitating / conveying auger 89 is disposed.

  Communication ports 94 and 95 are formed at both ends in the longitudinal direction of the partition wall 90. The first agitating path 92 and the second agitating path 93 are communicated with each other through the communication ports 94 and 95, and the developer G in the developer storage chamber 84 is rotated by the agitating and conveying augers 88 and 89, respectively. The developer G is conveyed while being stirred in the path 92 and the second stirring path 93, and the developer G is circulated between the first stirring path 92 and the second stirring path 93.

That is, the developer G stirred and transported by the stirring transport auger 88 is supplied to the developing roll 86 while being transported to the stirring transport auger 89.
(Main toner supply unit)
As shown in FIGS. 2 and 3, the main toner supply unit 70 adjacent to the developing unit 68 is provided with a toner storage chamber 150 in which the supply toner T is stored. A toner conveyance member 152 is provided in the toner storage chamber 150 along the axial direction of the developing roller 86.

  The toner conveying member 152 includes a rotation shaft 152A and is rotatably supported on the peripheral wall of the housing 80. Blades 152B are formed on the rotating shaft 152A at a predetermined pitch. A gear (not shown) is fixed to the end portion of the rotating shaft 152A. When the rotational force from a motor (not shown) is transmitted to the gear and the toner conveying member 152 rotates via the gear, the toner storage chamber 150 is driven by the blade 152B. The inner toner T is conveyed in the direction of arrow A in FIG. 3 while being stirred.

  Here, only one toner conveyance member 152 is provided in the toner storage chamber 150, but a plurality of toner conveyance members 152 may be provided in accordance with the capacity of the toner storage chamber 150.

  On the other hand, a wall portion 154 is provided between the toner storage chamber 150 and the developer storage chamber 84. From the lower part of the wall portion 154, the curved wall 156 extends toward the toner storage chamber 150, and the partition wall 157 extends toward the developer storage chamber 84, so that a tunnel-shaped dispense chamber is formed between the bottom plates of the housing 80. (Toner supply passage) 158 is provided.

  As shown in FIG. 3, a toner supply port 162 that connects the toner storage chamber 150 and the dispense chamber 158 is formed in the vicinity of one end of the curved wall 156 in the longitudinal direction. Thus, the toner T stored in the toner storage chamber 150 is transported through the toner storage chamber 150 while being agitated by the toner transport member 152, and is sent to the dispensing chamber 158 from the toner supply port 162.

  On the other hand, a toner discharge port 164 that connects the dispensing chamber 158 and the developer storage chamber 84 is formed near the other end in the longitudinal direction of the partition wall 157. As a result, the toner T in the dispense chamber 158 is conveyed through the dispense chamber 158 while being agitated by a dispense auger 160 (described later) constituting the toner supply means, and is sent from the toner discharge port 164 to the developer storage chamber 84. It is like that.

As shown in FIG. 2, the toner discharge port 164 is formed so that the lower end portion is positioned below the surface position of the developer G stored in the developer storage chamber 84. As a result, at least a part of the toner discharge port 164 is buried in the developer G accommodated in the developer accommodating chamber 84, and the toner T sent from the dispense chamber 158 to the developer accommodating chamber 84 is transferred. The developer G sinks into the developer G and is easily mixed with the developer G accommodated in the developer accommodating chamber 84.
(Dispense auger)
Here, the dispense auger 160 will be described. The dispense auger 160 includes a rotating shaft 166 similar to the stirring and transporting augers 88 and 89, and is rotatably supported on the peripheral wall of the housing 80. A spiral blade 168 is spirally wound from one end of the dispense auger 160 to the other end of the rotation axis 166 of the dispense auger 160.

  Further, a gear (not shown) is fixed to the end of the rotating shaft 166, and when a rotational force from a motor (not shown) is transmitted to the gear and the dispense auger 160 rotates via the gear, the spiral blade 168 The toner T stored in the toner storage chamber 150 is conveyed while being stirred.

  Here, the toner discharge port 164 is disposed inside the back wall 158A of the dispense chamber 158, and the other end portion of the dispense auger 160 corresponding to the section from the back wall 158A of the dispense chamber 158 to the toner discharge port 164. On the side, a reverse winding portion 170 in which the spiral shape of the spiral blade 168 is reversely wound is formed. The reverse winding portion 170 transports the toner T transported to the back wall 158 </ b> A side of the dispensing chamber 158 to the toner discharge port 164.

  Except for the reverse winding portion 170, the spiral blade 168 gradually decreases in pitch from the blade portion 168A of the spiral blade 168 as it goes from the upstream side to the downstream side in the transport direction of the toner T in the dispense chamber 158. I am doing so.

  For example, as shown in FIG. 4, a position beyond one end of the dispense auger 160 beyond the toner supply port 162 of the dispense chamber 158 is P1 (here, L1 = 85 mm), and a position corresponding to the toner discharge port 164 is P3. To do. P2 is provided between P1 and P3 (L2 = 40 mm, L3 = 55 mm). In addition, the section of P3-P4 is set as the reverse winding part 170.

  Here, the pitch of the blade portion 168A in the section P0 to P1 is 8 mm, the pitch of the blade portion 168A in the section P1 to P2 is 6 mm, and the pitch of the blade portion 168A in the section P2 to P3 is 4 mm.

As described above, the pitch of the blade portion 168A of the spiral blade 168 of the dispense auger 160 is gradually reduced from the upstream side to the downstream side in the conveyance direction of the toner T (in the arrow direction). The amount of toner T fed per rotation of the portion 168A is reduced so that the compression force of the toner T increases stepwise.
(Function)
Next, the operation of the image forming apparatus 10 according to the present embodiment will be described.

  As shown in FIG. 1, the charging roll 18 to which a voltage is applied first negatively charges the surface of the photoconductor 16 uniformly with a predetermined charging portion potential. Exposure is performed by the exposure device 36 so that the image portion on the charged photoreceptor 16 has a predetermined exposure portion potential, and an electrostatic latent image is formed.

  That is, a latent image corresponding to an image is formed on the photoconductor 16 by turning on and off a semiconductor laser (not shown) based on image data supplied from a control device (not shown).

  Further, as shown in FIG. 2, the developer G stirred and conveyed by the agitating and conveying auger 89 is adsorbed to the sleeve 86A of the developing roller 86 of the developing device 64 by the magnetic force of the magnet roll 86B. Further, the developer G adsorbed on the sleeve 86 </ b> A passes through the gap S between the developer regulating roll 50 and the developing roll 86, so that the surplus is scraped off and the layer thickness of the developer G becomes uniform.

  A predetermined developing bias voltage is applied to the developing roller 86 for each color from a power supply device (not shown), and the electrostatic latent image on the photosensitive member 16 is static when passing through the position of the developing roller 86. The toner of developer G adheres to the electrostatic latent image by electric force and is visualized as a toner image.

  Therefore, as shown in FIG. 1, the sheet material P placed in the paper feed cassette 26 is sent to the paper transport path 34 by the pickup roll 28, and is further predetermined by the transport roll 30 and the registration roll 32. The toner image is transferred to the sheet material P through the space between the photosensitive member 16 and the transfer roll 54. The transferred toner image is fixed by the fixing device 56, and the sheet material P on which the toner image is fixed is discharged to the discharge tray 60 by the discharge roll 58.

  By the way, in this embodiment, as shown in FIG. 4, the pitch of the blade portion 168A of the spiral blade 168 of the dispense auger 160 is stepped as it goes from the upstream side to the downstream side in the toner T conveyance direction (arrow direction). The amount of toner T fed per rotation of the blade portion 168A is reduced, and the compression force of the toner T is increased stepwise.

  It is known that the dispense auger 160 changes the toner supply amount for supplying the toner T to the developer storage chamber 84 depending on the pitch of the blade portions 168 </ b> A of the spiral blade 168. For example, FIG. 5A shows the relationship between the supply time and the supply amount of the toner conveyed by a dispense auger (not shown) and discharged to the toner discharge port. The cumulative toner supply amount with the passage of time is shown. In Comparative Example 1, the pitch of the blade portion of the dispense auger is 4 mm, and in Comparative Example 2, the pitch of the blade portion is 8 mm.

  Based on this data, FIG. 5B shows the toner supply amount (g / 20 s) discharged from the toner discharge port during 20 s. FIG. 5B shows data of Comparative Example 1, Comparative Example 2, Example 1 (first embodiment), and Example 2 (second embodiment to be described later) in order from the top.

  Here, Table 1 shows the average value of the toner supply amount obtained from the data shown in FIG. 5B. Comparative Example 1 is 0.098 (g / 20 s), and Comparative Example 2 is 0.225 (g / 20 s). That is, the toner conveyance force is higher in the case where the blade portion pitch is larger (Comparative Example 2) than in the case where the blade portion pitch is smaller (Comparative Example 1). The average value of the toner supply amount is calculated in the region where the toner supply amount discharged from the toner discharge port is stable, that is, in the region excluding the rising and falling portions in FIG. Is.

When the standard deviation σ (variation σ) of the toner supply amount of Comparative Examples 1 and 2 is obtained, Comparative Example 1 is 0.072 and Comparative Example 2 is 0.077. In Example 2, the toner supply amount variation σ is larger. However, when the ratio of the toner supply amount variation σ is obtained, the comparative example 1 is 73% and the comparative example 2 is 34%.

  That is, in the first place, the toner transport amount in Comparative Example 1 is smaller than that in Comparative Example 2 (the ratio of the toner supply amount in Comparative Example 1 to the toner supply amount in Comparative Example 2 is 44%). Considering the ratio (σ / Ave.), It can be seen that the effect of the variation in the toner supply amount is greater in Comparative Example 1 than in Comparative Example 2.

  Therefore, it is necessary to ensure a sufficient toner supply amount (0.225 g / 20 s or more) and to reduce the toner supply amount variation σ (less than 0.072) (σ / Ave. Is less than 34%). ).

  As in this embodiment, when the pitch of the blade portions 168A of the spiral blade 168 is gradually reduced from the upstream side to the downstream side in the conveying direction of the toner T, Example 1 in Table 1 shows. As shown, the average value of the toner supply amount is 0.235, and the variation σ of the toner supply amount is 0.063.

  As described above, the pitch of the blade portion 168A is gradually reduced from the upstream side to the downstream side in the toner conveyance direction, and the amount of toner T fed per rotation of the blade portion 168A is reduced, thereby reducing the toner. By increasing the compression force of T stepwise, the gap can be reduced on the downstream side in the transport direction, so that the toner supply amount is stabilized regardless of the amount of toner T in the toner storage chamber 150. I found out that I could do it.

  Here, as shown in FIG. 4, the pitch of the blade portion 168A of the spiral blade 168 from one end P0 to P1 of the dispense auger 160 is 8 mm, the pitch of the blade portion 168A from P1 to P2 is 6 mm, P2 The pitch of the blade portion 168A up to P3 is set to 4 mm, and the pitch of the blade portion 168A is gradually reduced from the upstream side to the downstream side in the toner T transport direction. Since the compression force of the toner T only needs to increase as it goes from the upstream side to the downstream side, it is not limited to this.

  For example, as shown in FIG. 6, the pitch of the blade portions 168 </ b> A of the dispense auger 160 may be gradually reduced from the upstream side to the downstream side in the toner T conveyance direction (arrow direction).

  Further, as shown in FIG. 7, the thickness of the blade portion 168A of the spiral blade 168 of the dispense auger 160 increases stepwise or gradually from the upstream side to the downstream side in the conveying direction of the toner T (arrow direction). You may make it thick.

  Here, Table 2 shows a result of obtaining the toner supply amount when the thickness of the blade portion 168A is changed. As shown in FIG. 8, the thickness of the blade portion 168A is adjusted so that the area of the hatched portion located between the blade portion 168A and the blade portion 168A changes.

(A)-(F) have shown the result measured using the dispense auger 160 whose pitch of the blade part 168A is 6 mm. (A) and (D) are based on the thickness of the blade portion 168A of (B) and (E), and the thickness of the blade portion 168A is increased so that the area of the hatched portion is -10%. ) And (F), the thickness of the blade portion 168A is reduced so that the area of the hatched portion is + 10% with reference to the thickness of the blade portion 168A of (B) and (E).

  (A) to (C) show the results of obtaining the toner supply rate (mg / s) by driving the dispense auger 160 at a rotation speed of 100 rpm, continuously supplying toner, and setting the measurement interval to 10 s. (D) to (F) show the results of obtaining the toner supply rate (mg / s) when the dispense auger 160 is intermittently driven for 410 ms (410 ms and then stopped for 410 ms) 10 times. Show.

  According to this, regardless of whether the dispense auger 160 is continuously driven or intermittently driven, it can be seen that the thicker blade portion 168A has a smaller amount of toner transport than the thinner case. That is, when the thickness of the blade portion 168A is increased, the volume for transporting the toner T is reduced, and thus the toner T is compressed.

  In addition to the above, as shown in FIG. 9, the outer diameter of the rotating shaft 166 of the dispense auger 160 increases from one end to the other as it goes from the upstream side to the downstream side in the conveying direction of the toner T (arrow direction). You may make it become large gradually (b> a) toward an edge part. When the outer diameter of the rotating shaft 166 is increased, the volume for transporting the toner T is reduced, so that the toner T is compressed.

  Further, as shown in FIG. 10, the cross-sectional area of the dispense chamber 158 is reduced from the upstream side to the downstream side in the toner conveyance direction (arrow direction), and the blade portion of the spiral blade 168 of the dispense auger 160 is also formed. The outer diameter of 168A may be reduced. As a result, the volume for transporting the toner T is reduced, and the toner T is compressed.

In addition, although Example was demonstrated about FIG.4, FIG.6, FIG.7, FIG.9 or FIG. 10, respectively here, Example of FIG.7, FIG.9 or FIG.10 is implementation of FIG.4 or FIG.6, respectively. You may combine with an example.
(Second Embodiment)
Next, a second embodiment will be described. In addition, description is abbreviate | omitted about the content substantially the same as 1st Embodiment.

  As shown in FIGS. 2 and 3, a toner supply port 162 connecting the toner storage chamber 150 and the dispense chamber 158 is formed in the curved wall 156 of the wall portion 154 provided between the toner storage chamber 150 and the developer storage chamber 84. In the partition wall 90 of the wall portion 154, a toner supply port 162 that connects the dispense chamber 158 and the toner storage chamber 150 is formed.

  Therefore, in the present embodiment, as shown in FIG. 11, the curved wall 156 is projected and viewed in a substantially circular shape connecting the toner storage chamber 150 and the dispense chamber 158 between the toner supply port 162 and the toner discharge port 164. A plurality of through holes 174 are provided.

  As shown in FIG. 4, a dispense auger 160 in which the pitch of the blade portions 168 </ b> A of the spiral blade 168 is gradually reduced is used, and the position of the through hole 174 is defined by the dispense auger 160 as shown in FIG. 12. Corresponding to the positions of P1 and P2.

  When the toner T is excessively compressed, the toner T adheres to the blade portion 168A, and the blade portion 168A does not carry the toner T, or the toner T is soft-blocked, and the carrier in the developer accommodating chamber 84 If the agitation is inadequate and severe, soft blocking may be eliminated by the trimmer, which may cause color streaking.

  Therefore, by providing the through-hole 174 connecting the toner storage chamber 150 and the dispense chamber 158 shown in FIG. 2 in the curved wall 156, the toner T in the dispense chamber 158 passes through the through-hole 174 when the supply of the toner T is excessive. The toner T is pushed out into the toner storage chamber 150 so that the toner T in the dispense chamber 158 is not excessively compressed.

  Here, P <b> 1 and P <b> 2 of the dispense auger 160 are places where the pitch of the blade portions 168 </ b> A changes and are points where the compression force of the toner T changes. At the change point of the toner compression force, the compression force of the toner T becomes higher than the upstream side in the transport direction of the toner T. Therefore, by providing the through hole 174 at a position including the change point of the compression force of the toner T, dispensing is performed. The toner T in the chamber 158 can be more effectively pushed into the toner storage chamber 150.

  Here, the through hole 174 that connects the toner storage chamber 150 and the dispense chamber 158 has a substantially circular shape, but it is only necessary that the wall hole that connects the toner storage chamber 150 and the dispense chamber 158 is formed at a predetermined position. The shape is not limited to this.

  For example, a rectangular slit 176 may be used as shown in FIG. Although three slits 176 are formed here, the ribs 178 for partitioning the slits 176 are for maintaining the strength of the dispensing chamber 158, and the slits 176 are not necessarily required to be three.

  Further, here, the through hole 174 or the slit 176 is formed at the position including P1 and P2 of the dispense auger 160, which is the changing point of the toner compressive force, but the toner compression of P2 is more than the toner compressive force of P1. Since the force is larger, it is sufficient that the through hole 174 or the slit 176 is formed at a position including at least P2. For example, as shown in FIG. 14, a long hole 180 may be formed at a position including P2, and a long hole 182 may be formed between P1 and P2.

  On the other hand, in Table 3, as shown by (A) to (G), conditions such as the shape of the wall hole penetrating the curved wall 156 are changed, and under this condition, the toner discharge amount and the toner storage chamber through the wall hole are changed. The result of obtaining the reflux rate of the toner from the reflux amount of the toner extruded into the toner is shown.

(A)-(D) make the wall hole the round-shaped through-hole 174 shown in FIG. 11, and (E)-(G) make the wall hole the rectangular slit 176 shown in FIG. In (A) to (C), (E), and (F), the dispense auger 160 in which the pitch of the blade portion 168A of the spiral blade 168 is narrowed in steps (8 → 6 → 4) is used (D ) And (G) use a dispense auger in which the pitch of the blades is fixed (8 mm).

  In (C), the rotation speed of the dispense auger is set to 100 rpm, but in (C), the rotation speed of the dispense auger is set to 50 rpm. Further, (B) and (F) supply toner little by little, and toners other than (B) and (F) are fully supplied.

  From the results of (A) and (C), it was found that there was almost no difference in the reflux rate depending on the rotational speed of the dispense auger. Further, from the results of (A) and (B), when the pitch of the blade portion of the dispense auger is changed, when the toner supply amount from the toner supply port is excessive, the reflux rate is high and the toner supply from the toner supply port is high. It was found that the reflux rate was low when the amount was small.

  Comparing the total area of the wall holes, the three slits 176 in FIG. 13 have a larger area than the four through holes 174 in FIG. From the results of (A) and (E), the larger the wall hole area, the higher the reflux rate, but from the results of (B) and (F), even when the amount of toner supplied from the toner supply port is small. A large amount of toner is not recirculated according to the area of the wall hole.

  15A to 15C show a state where the toner in the dispensing chamber 158 returns to the toner storage chamber 150 through the through hole 174 or the slit 176. FIG. Here, P1 and P2 respectively indicate the change points of the pitch of the blade portion 168A of the dispense auger 160 shown in FIG. That is, P1 and P2 are changing points of the toner compression force.

  The dispense auger 160 is configured so that the pitch of the blade portions 168A of the spiral blade 168 becomes narrower stepwise from the upstream side to the downstream side in the toner T conveyance direction, so that FIGS. ), It can be seen that the most toner T flows back from the through hole 174 and the slit 176 corresponding to P2.

  Here, FIG. 15B shows a result of closing the through hole 174 corresponding to P2 of FIG. According to this, it was found that the toner recirculation is mainly performed at the change point of the toner compressive force of the dispense auger 160, particularly at a position corresponding to P2, and hardly at other positions. For this reason, it can be said that it is desirable to form the through hole 174 or the slit 176 at a position including at least P2 which is a change point of the compressive force of the dispense auger 160.

  As described above, by providing the through hole 174 or the slit 176 at a position including the change point of the toner compressive force (a position including at least P2), the toner T in the dispense chamber 158 is more effectively transferred to the toner storage chamber 150. Can be extruded.

  In the above embodiment, as shown in FIG. 2, the developing device 64 in which the toner storage chamber 150 and the developer storage chamber 84 are integrated has been described. However, as an example, FIG. 16A and FIG. As illustrated, the developing device 188 may include a toner cartridge 186 that can be attached to and detached from the developer containing device 184.

  In this case, a dispense chamber 190 for supplying the toner in the toner cartridge 186 is provided on the developer storage device 184 side, and a dispense auger 192 is disposed in the dispense chamber 190. When the toner cartridge 186 is rotated with respect to the developer container 184 after the toner cartridge 186 is attached to the developer container 184, the toner discharge port of the toner cartridge 186 and the toner supply port 190A of the dispense chamber 190 are connected.

  If the second embodiment is applied to this configuration, a through hole for returning the toner in the dispensing chamber 190 must be formed, and a through hole communicating with the through hole must also be formed on the toner cartridge 186 side. It will disappear.

  For this reason, in this embodiment, as shown in FIGS. 16A and 16B, a reflux toner chamber 194 is formed adjacent to the dispense chamber 190, and as shown in FIG. A through-hole 196 connecting the dispensing chamber 190 is formed. A reflux auger 198 for stirring and conveying the toner is provided in the reflux toner chamber 194 so that the toner refluxed from the dispense chamber 190 to the reflux toner chamber 194 through the through hole 196 is returned to the dispense chamber 190 again.

  As described above, the present invention is not limited to the above-described embodiment, and various modifications, changes, and improvements can be made without departing from the gist of the present invention.

1 is an overall configuration diagram of an image forming apparatus including a developing device according to an embodiment. 1 is a schematic configuration diagram illustrating a developing device according to an exemplary embodiment. It is a cross-sectional view showing a developing device according to the present embodiment. It is a front view of the dispense auger of the developing device concerning a 1st embodiment. (A) shows the relationship between the supply time of the toner discharged from the toner discharge port and the supply amount, and (B) shows the toner supply amount (g / 20 s) discharged from the toner discharge port during 20 s. It is shown. It is a front view of the dispense auger which shows the 1st modification of the developing device which concerns on 1st Embodiment. It is a front view of the dispense auger which shows the 2nd modification of the developing device which concerns on 1st Embodiment. It is explanatory drawing for demonstrating the content of Table 2. FIG. It is a front view of the dispense auger which shows the 3rd modification of the developing device which concerns on 1st Embodiment. It is a front view of the dispense auger which shows the 4th modification of the developing device which concerns on 1st Embodiment. It is a top view which shows the wall part of the developing device which concerns on 2nd Embodiment. It is a top view which shows the wall part and dispensing auger of the developing device which concern on 2nd Embodiment. It is a top view which shows the 1st modification of the wall part of the developing device which concerns on 2nd Embodiment. It is a top view which shows the 2nd modification of the wall part of the developing device which concerns on 2nd Embodiment. (A)-(C) are state diagrams in which the toner in the dispensing chamber is recirculated to the toner storage chamber. (A) and (B) are side sectional views showing a first modification of the developing device according to the present embodiment, and are operation diagrams for mounting the toner cartridge to the developer accommodating device. FIG. 10 is a partial cross-sectional view of a developer accommodating device showing a first modification of the developing device according to the present embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 16 Photoconductor (Image holding body)
64 Development device 84 Developer storage chamber (development chamber)
86 Development Roll (Developer Holder)
150 Toner storage chamber 154 Wall 158 Dispensing chamber (toner supply passage, toner supply means)
160 Dispensing Auger (Toner Supply Unit)
162 Toner supply port (supply port)
164 Toner discharge port (discharge port)
166 Rotating shaft (toner supply means)
168 Spiral blade (blade member, toner supply means)
168A Blade 174 Through hole 176 Slit (through hole)
180 long hole (through hole)
180 long hole (through hole)
184 Developer storage device (developing device)
186 Toner cartridge (developing device)
188 Developing device 190 Dispensing chamber (toner supply passage, toner supply means)
190A Toner supply port (supply port)
192 Dispensing auger (toner supply means)
194 Reflux toner chamber (toner storage chamber)
196 Through hole

Claims (8)

A toner storage chamber in which toner is stored;
A developing chamber for holding a developer containing toner and a magnetic carrier in a developer holder;
Connecting the toner storage chamber and the developing chamber, stirring the toner supplied from the toner storage chamber side, gradually or stepwisely compressing the toner as it goes from the upstream side to the downstream side in the toner transport direction. A toner supplying means for supplying the developing chamber at a high level;
A developing device comprising: The toner supply means includes a toner supply passage connecting the toner storage chamber and the developing chamber, a rotation shaft rotatably provided in the toner supply passage, and a blade formed in a spiral shape around the rotation shaft And a member,
2. The developing device according to claim 1, wherein the pitch of the blade portion of the blade member is gradually or stepwise narrowed from the upstream side to the downstream side in the toner conveyance direction. The toner supply means includes a toner supply passage connecting the toner storage chamber and the developing chamber, a rotation shaft rotatably provided in the toner supply passage, and a blade formed in a spiral shape around the rotation shaft And a member,
3. The developing device according to claim 1, wherein a thickness of a blade portion of the blade member increases gradually or stepwise from an upstream side to a downstream side in a toner conveyance direction. . The toner supply means includes a toner supply passage connecting the toner storage chamber and the developing chamber, a rotation shaft rotatably provided in the toner supply passage, and a blade formed in a spiral shape around the rotation shaft And a member,
The outer diameter of the rotating shaft increases gradually or stepwise from the upstream side to the downstream side in the toner conveyance direction. Development device. The toner supply means includes a toner supply passage connecting the toner storage chamber and the developing chamber, a rotation shaft rotatably provided in the toner supply passage, and a blade formed in a spiral shape around the rotation shaft And a member,
The cross-sectional area of the toner supply passage and the outer diameter of the blade portion of the blade member are gradually or stepwise reduced from the upstream side to the downstream side in the toner transport direction. Item 5. The developing device according to any one of Items 1 to 4. A wall portion constituting the toner supply passage is provided with a supply port through which toner is supplied from the toner storage chamber and a discharge port through which the toner conveyed through the toner supply passage is discharged into the developing chamber,
The through hole that connects the toner storage chamber and the toner supply passage is provided in the wall portion located between the supply port and the discharge port. Development device.   The developing device according to claim 6, wherein the through-hole is provided at a position including a change point of a toner compressive force.   An image holding body on which an electrostatic latent image is formed on a surface, and a developing device according to claim 1 that makes a toner image appear on the image holding body. Image forming apparatus.