JP2007114670A - Toner conveying device, and developing device, process cartridge and image forming apparatus having the toner conveying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To adjust an amount that developer is attached to the surface of a latent image carrier, by properly controlling the electric field of a developing area. <P>SOLUTION: A toner conveying device includes a toner conveying member 2 having a plurality of electrodes that generate an electric field for conveying and hopping toner with electrostatic force, and a surface potential measuring member that measures the surface potential on the toner conveying member 2. A developing device, a process cartridge, and an image forming apparatus that have this conveying device are also provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a toner conveying device, a developing device including the toner conveying device, and an image forming apparatus including the developing device.

2. Description of the Related Art Conventionally, there has been known a developing device configured to perform development by supplying a developer onto a latent image carrier without directly contacting the developer on the developer carrier with the latent image carrier.
As an example, there is a conventional technique in which toner is supplied onto a latent image carrier by a toner conveying member.
The toner conveying member is arranged to face the latent image carrier, and a plurality of electrodes are arranged on the surface thereof at a predetermined pitch.
An n-phase AC voltage is applied to this electrode to generate a traveling wave electric field that conveys the toner. The toner opposes the latent image carrier while hopping in the vertical direction by this traveling wave electric field. It is conveyed to the development area.
In the development area, the hopped toner is subjected to a force toward the toner conveying member in the non-image area and a force toward the latent image carrier in the image area, and the latent image is visualized and developed.

As described above, when the toner is transported while hopping by the transport electric field, the force acting on the toner is dominated by the force from the electric field, and the charge amount of the toner in the development area, the toner transport member and the latent image The potential difference created with the carrier is very important.
Concerning fluctuations in the charge amount of the transported toner, a method of “converting and detecting the toner charge amount on the toner transport member by detecting the toner transport speed” or “detecting the toner hopping height and transport amount” There is known a technique of feeding back to charge amount adjustment by a method of “converting and detecting the charge amount of toner on a toner conveying member” or a method using a combination of the above two methods.
With such a technique, the following problems have been solved.

When the charge amount of the toner fluctuates, the toner conveyance state (hopping height and conveyance speed) changes. When the charge amount of the toner is large, the toner can be hopped higher because it receives a large force from the transport electric field. Further, since the repulsion between the toners increases, the density of the toner being conveyed decreases. Since the charge amount of the toner is large, a larger mirror image force acts on the toner attracted and adhered to the surface of the transport member by the transport electric field.
When the voltage applied to the electrodes is switched, it is necessary for the toner to overcome this mirror image force and hop, and it takes time to move from the stationary state. Further, since the force received from the carrier electric field is large, the toner accurately follows the switching of the voltage applied to the electrode.
When the charge amount of the toner is small, since the force received from the conveying electric field is small, the toner does not hop very much. Since the repulsion between the toners is small, the density of the toner being conveyed increases. In addition, since the image power is small, it is possible to move immediately from a stationary state by switching the voltage. In addition, since the force applied to the hopping toner is small, toner that is transported by skipping a plurality of electrodes is also generated, and the toner transport speed is increased.
In the development area, when the charge amount of the toner is large, the force received from the transport electric field is large, and therefore, the toner moves toward the latent image carrier with a large kinetic energy. A part of such toner adheres to the background portion (non-image portion), and background staining occurs. In the image area, toner dust also occurs due to repulsion between toners attached to the latent image.
When the charge amount of the toner is small, since the force received from the transport electric field is small, the toner does not hop so much and cannot approach the latent image carrier, so the toner adhesion amount decreases.
Since such a problem occurs, it can be said that the charge amount of the toner needs to be controlled to an appropriate value.

  In addition, a technique for detecting the amount of developer adhering to the latent image carrier and controlling the amount of developer conveyed to the developing area has been disclosed. In this case, the detected amount of adhering is large. The amount of developer to be conveyed is reduced, and when the amount of adhesion is small, the amount of developer to be conveyed is increased (for example, see Patent Documents 1 and 2).

However, in the techniques disclosed in these documents, the force acting on the toner when the toner is transported while hopping, that is, the force from the electric field is important. The potential difference produced has not been sufficiently controlled.
That is, even if the amount and amount of charge of the transport toner can be controlled within a certain range, the handling of the state of the transport toner and the change in the state of the transport member surface that are constantly changing is incomplete.
For example, in the development region where the electric resistance of the conveying member surface, the charge-up potential of the conveying member surface due to the conveying toner, or the charge-up potential fluctuation of the conveying member surface due to the sequential variation of the electric resistance or toner charge amount, etc. This is a response to electric field fluctuations.
In addition, due to environmental fluctuations or the like, the response to the potential fluctuation of the toner cloud itself produced by the hopping toner in the development area, that is, the electric field fluctuation in the development area is incomplete.

JP 2004-101933 A JP 2004-170796 A

  Therefore, in the present invention, by providing means for measuring the surface potential on the toner conveying member, a potential difference created between the toner conveying member and the latent image carrier in the development region is detected, and the detection result is applied to the conveying electrode. By changing the voltage parameter to be applied, the electric field in the development area was appropriately controlled.

In the present invention, there is provided a surface potential measuring means comprising a toner transport member having a plurality of electrodes for generating an electric field for transporting and hopping toner by electrostatic force, and measuring the surface potential on the toner transport member. A toner conveying device is provided.
According to a second aspect of the present invention, at least when the toner is transported on the toner transport member, the surface potential on the toner transport member is measured by the surface potential measuring means.
In the invention of claim 3, the time for measuring the surface potential on the toner conveying member is variable.
According to a fourth aspect of the present invention, there is provided a toner conveying apparatus comprising a surface potential control means for controlling a surface potential on the toner conveying member based on a measurement result by the surface potential measuring means.
5. The toner transport according to claim 4, wherein the surface potential control means on the toner transport member is adapted to change a voltage parameter applied to a plurality of electrodes. apparatus.
According to a sixth aspect of the present invention, there is provided a developing device that is arranged to face an electrostatic latent image carrier and develops an electrostatic latent image on the electrostatic latent image carrier, A developing device including the toner conveying device according to the invention is provided.
According to a seventh aspect of the present invention, there is provided toner supplying means for supplying toner to the toner conveying device, and the toner supplied by the toner supplying means reaches a position facing the electrostatic latent image carrier on the toner conveying member. The toner that has been transported and not used for development is transported as it is on the toner transport member, and the surface potential control means on the toner transport member is in the direction of toner transport on the toner transport member. Provided is a developing device provided on the downstream side of the toner supply means and upstream of the position facing the electrostatic latent image carrier.
According to an eighth aspect of the present invention, there is provided an image forming apparatus comprising the developing device according to the sixth or seventh aspect of the present invention.
According to a ninth aspect of the present invention, there is provided a process cartridge having a structure in which at least one of a latent image carrier, a charging unit, and a cleaning unit in an electrophotographic process and the developing device according to the sixth or seventh aspect of the present invention are integrally held. I will provide a.
According to a tenth aspect of the present invention, there is provided an image forming apparatus including one or a plurality of process cartridges according to the ninth aspect of the present invention.

  According to the present invention, it is possible to appropriately control the electric field in the development region, and to adjust the adhesion amount of the developer on the latent image carrier to an ideal state.

  Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following examples.

1 and 2 are schematic configuration diagrams of an example of a developing device provided with the toner conveying device of the present invention. In these, the common component shall attach | subject the same number.
In the developing device 10 shown in FIG. 1, it is assumed that a two-component developer composed of a magnetic carrier and a nonmagnetic toner is used.
The developer accommodating portion 4 constituting the developing device 10 of FIG. 1 is divided into two chambers and is connected by developer passages at both ends in the developing device.
The developer storage unit 4 stores a two-component developer and is transported through the developer storage unit 4 while being stirred by the stirring transport screws 5A and 5B in each chamber.

The developing device 10 is provided with a toner supply port 6, and is supplied to the developer storage unit 4 from a toner storage unit (not shown) through the toner supply port 6.
A toner concentration sensor (not shown) that detects the magnetic permeability of the developer is installed in the developer storage unit 4 to detect the concentration of the developer.
When the toner concentration in the developer accommodating portion 4 decreases, the toner is replenished from the toner replenishing port 6 to the developer accommodating portion 4.

A developer carrier 3 is disposed in a region facing the agitating and conveying screw 5A.
A fixed magnet is disposed inside the developer carrier 3, and the developer in the developer container 4 is pumped up to the surface of the developer carrier 3 by the rotation and magnetic force of the developer carrier 3. .
A developer layer regulating member 7 is provided in a region facing the developer carrier 3 downstream of the developer pumping region in the rotation direction of the developer carrier 3.
The developer pumped in the pumping area is regulated to a certain amount of developer layer thickness by the developer layer regulating member 7.
The developer that has passed through the developer layer regulating member 7 is conveyed to a region facing the toner conveying member 2 as the developer carrying member 3 rotates.

A supply bias is applied to the developer carrier 3 by the first voltage application unit 11.
A voltage is applied to the toner conveying member 2 by the second voltage applying means 12 to the electrode 20.
In a region facing the toner conveying member 2, an electric field is generated between the developer carrier 3 and the toner conveying member 2 by the first and second voltage applying units 11 and 12.
Under the electrostatic force from the electric field, the toner dissociates from the carrier and moves to the surface of the toner conveying member 2.
The toner that has reached the surface of the toner transport member 2 is transported while hopping on the surface of the toner transport member 2 by a transport electric field generated by the voltage applied by the second voltage applying unit 12.
The toner conveyed by the conveying electric field to the area facing the latent image carrier 1 is developed on the latent image carrier 1 by the developing electric field between the toner conveying member 2 and the image portion on the latent image carrier 1. The
The toner conveying member 2 and the latent image carrier 1 face each other in a non-contact manner with a gap of 50 to 1000 μm, preferably 150 to 400 μm.
Further, the toner conveying member 2 does not rotate, and the toner is conveyed on the outer peripheral surface in the direction of the arrow by a conveying electric field (phase-shifting electric field). On the other hand, the developer carrier 3 rotates in the direction indicated by the arrow.

FIG. 2 is a schematic configuration diagram of another example of the developing device of the present invention, in which a one-component developer made of a non-magnetic toner is applied.
The toner is accommodated in the developer accommodating portion 14, and the toner is frictionally charged with the developer carrier 13 by the toner replenishing roller, and is pumped onto the developer carrier 13 by electrostatic force.
The toner on the developer carrier 13 is made into a thin layer by the developer layer regulating member 7 and is conveyed to a region facing the toner conveying member 2 as the developer carrier 13 rotates.
A supply bias is applied to the developer carrier 13 by the first voltage application unit 11.
A voltage is applied to the toner conveying member 2 by the second voltage applying means 12 to the electrode 20.
In a region facing the toner conveying member 2, an electric field is generated between the toner conveying member 2 and the developer carrier 13 by the first and second voltage applying units 11 and 12.
Under the electrostatic force from the electric field, the toner dissociates from the developer carrier 13 and moves to the surface of the toner conveying member 2.
The toner that has reached the surface of the toner transport member 2 is transported while hopping on the surface of the toner transport member 2 by a transport electric field generated by the voltage applied by the second voltage applying unit 12.
The toner conveyed by the conveying electric field to the area facing the latent image carrier 1 is developed on the latent image carrier 1 by the developing electric field between the toner conveying member 2 and the image portion on the latent image carrier 1. The

Here, details of the toner conveying member 2 will be described in detail with reference to FIG.
FIG. 3 is an explanatory cross-sectional view showing an enlarged part of the toner conveying member 2.
In this toner conveying member 2, a plurality of electrodes 102 are arranged on a support substrate 101 as a set and arranged at a predetermined interval along the toner moving direction, and an insulating material for forming an electrostatic conveying surface 103a thereon. A surface protective layer 103 made of an inorganic or organic insulating material, which becomes a protective electrostatic transport surface forming member and serves as a protective film covering the surface of the electrode 102, is laminated.

As the support substrate 101, a substrate made of an insulating material such as a glass substrate, a resin substrate or a ceramic substrate, or a substrate made of a conductive material such as SUS, an insulating film such as SiO ₂ , a polyimide film, etc. A substrate made of a material that can be deformed flexibly is applicable.
The electrode 102 is formed by depositing a conductive material such as Al or Ni—Cr on the support substrate 101 with a thickness of 0.1 to 10 μm, preferably 0.5 to 2.0 μm, and using a photolithography technique or the like. It is formed by patterning into the required electrode shape.
The width (electrode width) a of the plurality of electrodes 102 in the toner conveying direction is 1 to 20 times the average particle size of the powder to be moved, and the average particle of the toner to which the pitch p of the electrode 102 is also moved. 1 to 20 times the diameter.

For example, SiO ₂ , TiO ₂ , TiO ₄ , SiON, BN, TiN, Ta ₂ O _{5 and the} like can be applied to the surface protective layer 103, and the thickness is 0.5 to 10 μm, preferably 0.5 to 3 μm. ing.

In FIG. 3, lines extending from the respective electrodes 102 represent conductive lines for applying a voltage to the respective electrodes 102, and only the portions indicated by black circles among the overlapping portions of the respective lines are electrically connected. This part is electrically insulated.
Different drive voltages V11 to V13 and V21 to V23 having different n phases are applied to the respective electrodes 102 from the power source 104 on the main body side.
In this embodiment, a case where a three-phase driving voltage is applied (n = 3) will be described. However, the present invention can be applied to any natural number n satisfying n> 2 as long as toner particles are transported. It is.
In the present embodiment, each electrode 102 is connected to one of the contacts S11, S12, S13, S21, S22, and S23 on the developing device side, and each of the contacts S11, S12, S13, S21, S22, and S23 is developed. When the apparatus is mounted on the main body of the image forming apparatus, it is connected to a main body side power supply 104 that provides drive waveforms V11, V12, V13, V21, V22, and V23, respectively.
The toner transport member 2 transports toner particles to the vicinity of the image carrier 1, and also transports toner particles to the latent image of the image carrier 1, a transport region for collecting toner particles that have not contributed to development after passing through the development region. And a development area for forming a toner image.
The development area exists only in the area close to the image carrier 1, and the conveyance area exists on the circumference of the toner conveyance member 2 and in the entire area other than the development area.

An area where the toner can move by the phase-shift electric field is referred to as an “electrostatic transfer surface”.
In the present embodiment, the entire peripheral surface of the toner conveying member 2 is an electrostatic conveying surface.
In the transport region, the drive waveforms V11, V12, and V13 are applied to the electrodes 102 by the power source 104, and in the development region, the drive waveforms V21, V22, and V23 are applied to the electrodes 102 by the power source 104.
Therefore, the principle of electrostatic conveyance of toner in the toner conveyance member 2 will be described. By applying an n-phase pulse voltage to the plurality of electrodes 102 of the toner conveying member 2, a phase shift electric field (traveling wave electric field) is generated by the plurality of electrodes 102, and the charged toner on the toner conveying member 2 is charged. Receives a repulsive force and / or a suction force and moves in the transfer direction.
For example, as shown in FIG. 4, with respect to the plurality of electrodes 102 of the toner conveying member 2, a three-phase pulse of A phase, B phase, and C phase that changes between the ground G (0 V) and a positive voltage +. The drive waveform (voltage) is applied while shifting the timing.
At this time, as shown in FIG. 5, the negatively charged toner T is present on the toner conveying member 2, and “G”, “G”, “+”, “G” ”And“ G ”are applied (FIG. 5A), the negatively charged toner T is positioned on the“ + ”electrode 102. At the next timing, “+”, “G”, “G”, “+”, and “G” are respectively applied to the plurality of electrodes 102 ((b) in the figure). Since a repulsive force acts between the “G” electrode 102 and an attractive force acts between the “+” electrode 102 on the right side, the negatively charged toner T moves to the “+” electrode 102 side. Further, as shown in FIG. 5C, “G”, “+”, “G”, “G”, and “+” are applied to the plurality of electrodes 102 at the next timing, respectively, and negatively charged toner Similarly, the repulsive force and the attractive force act on T, so the negatively charged toner T further moves to the “+” electrode 102 side.

This will be specifically described with reference to FIG.
As shown in FIG. 6A, the electrodes A to F of the toner conveying member 2 are all 0 V (G), and the negatively charged toner T is placed on the toner conveying member 2 as shown in FIG. When “+” is applied to the electrodes A and D, the negatively charged toner T is attracted by the electrodes A and D and moves onto the electrodes A and D.
At the next timing, as shown in FIG. 6C, when the electrodes A and D are both “0” and “+” is applied to the electrodes B and E, the toner T on the electrodes A and D Receives the repulsive force and the suction force of the electrodes B and E, so that the negatively charged toner T is transferred to the electrode B and the electrode E.
Further, at the next timing, as shown in FIG. 6D, when the electrodes B and E are both “0” and “+” is applied to the electrodes C and F, The toner T receives a repulsive force and also receives the suction force of the electrodes C and F, so that the negatively charged toner T is transferred to the electrodes C and F. In this way, the negatively charged toner is sequentially transferred rightward in the drawing by the traveling wave electric field.
By applying a multi-phase driving waveform (voltage) whose voltage changes to the plurality of electrodes 102 in this way, a traveling wave electric field is generated on the toner conveying member 2, and the negatively charged toner progresses in the traveling wave electric field. Move in the direction. In the case of positively charged toner, the drive waveform changes in the same direction by reversing the drive waveform change pattern.

Next, an example of the power source 104 (second voltage applying unit 11) will be described with reference to FIG.
The power source 104 includes a pulse signal generation circuit 105 that generates and outputs a pulse signal, and a waveform amplifier that receives the pulse signal from the pulse signal generation circuit 105 and generates and outputs pulse voltages V11, V12, and V13 as drive waveforms. 106a, 106b, and 106c, and waveform amplifiers 107a, 107b, and 107c that generate and output drive waveforms V21, V22, and V23 by inputting the pulse signal from the pulse signal generation circuit 105.
The pulse signal generation circuit 105 receives, for example, logic level input pulses, and includes two sets of pulses that are phase-shifted by 120 °, and switches switching means such as transistors included in the waveform amplifiers 106a to 106c and 107a to 107c in the next stage. It generates and outputs a pulse signal having an output voltage of 10 to 15 V that can be driven to perform switching of 100 V.
The waveform amplifiers 106a, 106b, and 106c apply three-phase drive waveforms (drive pulses) V11, V12, and V13 to the respective electrodes 102 in the transport area, and the waveform amplifiers 107a, 107b, and 107c correspond to the electrodes in the development area. Three-phase drive waveforms (drive pulses) V21, v22, and V23 are applied to the electrode 102.

  Here, in the transport region of the toner transport member 2, for each electrode 102, as shown in FIG. 8, the application time ta of +100 V for each phase is set to about 33%, which is 1/3 of the repetition period tf. (This is referred to as a “carrier voltage pattern”.) Three-phase drive waveforms (drive pulses) V11, V12, and V13 are applied. This drive waveform is a waveform suitable for high-speed conveyance of toner in the conveyance region.

Further, in the development region, as shown in FIG. 9, for each electrode 102, the application time ta of + 100V or 0V of each phase is set to about 67%, which is 2/3 of the repetition period tf. Three-phase drive waveforms (drive pulses) V21, V22, and V23 are applied. In the developing region, it is preferable to positively launch toner particles toward the image carrier, and the driving waveform in FIG. 9 is suitable for launching toner particles.
Even when a drive waveform of the development voltage pattern is applied, since the toner is also subjected to a lateral force other than the toner positioned at the center of the 0V electrode, not all the toners are launched at the same time, but move in the horizontal direction. Conversely, even when a drive waveform of a carrier voltage pattern is applied, depending on the position of the toner, there is a toner whose ascending distance is larger than that of being obliquely launched at a large angle and moving horizontally.
Therefore, the drive waveform pattern applied to each electrode 102 in the transport region is not limited to the transport voltage pattern shown in FIG. 8 described above, and the drive waveform pattern applied to each electrode 102 in the development region 12 is also the above-described diagram. The development voltage pattern shown in FIG.
The voltage values Vhi and Vlo and the frequency tf can be set to arbitrary values by process control.
In this embodiment, the voltage is a pulse, but it may be a sine wave or a triangular wave.

In the above description, the case where the driving waveform is three-phase has been described. When this is generalized to n-phase, the driving waveform is as follows.
That is, when an n-phase (n is an integer of 3 or more) pulsed voltage (driving waveform) is applied to each electrode to generate a traveling wave electric field, the voltage application time per phase {repetition period time × By setting the voltage application duty to be less than (n−1) / n}, it is possible to increase the efficiency of conveyance and development.
For example, when a three-phase drive waveform is used, the voltage application time ta of each phase is set to less than about 67%, which is 2/3 of the repetitive cycle time tf, and when a four-phase drive waveform is used, It is preferable to set the voltage application time of each phase to less than 75%, which is 3/4 of the repetition cycle time.
On the other hand, the voltage application duty is preferably set to {repetition cycle time / n} or more. For example, when a three-phase driving waveform is used, it is preferable to set the voltage application time ta of each phase to about 33% or more, which is 1/3 of the repetition cycle time tf.
That is, between the voltage applied to the target electrode and each voltage applied to the upstream adjacent electrode and the downstream adjacent electrode in the traveling direction, a time is set for the upstream adjacent electrode to repel and the downstream adjacent electrode to be sucked. The efficiency can be improved. In particular, when the driving frequency is high, the initial speed for the toner on the electrode of interest is set by setting it within the range of {repeat cycle time / n} or more and less than {repeat cycle time × (n−1) / n}. It becomes easy to obtain.

When the toner is transported while being hopped by a transport electric field, the toner loses electric charge when it collides with the surface of the transport member.
This can be considered as contact friction between the toner and the surface of the conveying member. When the toner passes through the developer layer regulating member, the toner is charged by frictional charging with the carrier.
The charged toner is supplied to the toner conveying member in the supply area. The supplied toner is conveyed while repeatedly colliding with the surface of the toner conveying member and hopping by the conveying electric field.
Therefore, the number of collisions between the toner and the surface of the toner conveying member is proportional to the toner conveying distance. When the conveying distance is short, the decrease in the charge amount is small, and when the conveying distance is long, the decrease in the charging amount is large. The charge amount of the toner obtained by friction with the carrier decreases due to the collision with the toner conveying member being conveyed, and finally converges to a certain value. This convergence value is determined by the frictional charging characteristics between the toner and the surface material of the toner conveying member. The toner is transported to the development area with a charge amount of the convergence value.
Since the convergence value of the toner being conveyed is determined by the frictional charging characteristics between the toner and the surface material of the toner conveying member, it is influenced by the environment in the image forming apparatus. When the environment in the image forming apparatus fluctuates, the convergence value of the toner charge amount also changes. Therefore, it is necessary to detect the convergence value of the charge amount of the toner being conveyed.
As a detection method, an electrode or the like is placed at a position facing the toner conveying member, a voltage is applied to the electrode to measure the amount of toner adhered, a method of optical measurement using a light emitting element and a light receiving element, or the like However, any method is not particularly limited because it does not affect the present invention.

In this development method in which the toner having the charge amount converged to a certain value as described above is hopped on the conveying member to the development area and adhered to the latent image on the electrostatic latent image carrier, the toner in the development area is The toner is attached to the image carrier latent image portion by a developing electric field formed between the toner conveying member and the image portion on the latent image carrier. This is a development system that does not require the force necessary to overcome the adhesion force with a carrier or the like that is required when heading to, and reacts sensitively to an electric field.
At this time, the effective potential Vdev on the toner conveying member includes the conveying member potential applied by the second voltage applying unit, the toner layer potential generated by the cloud of the conveying toner, and the charge-up potential that the toner charge gives to the conveying member surface. Determined by the total. Although the potential of the second voltage application means is arbitrarily variable, the transport toner layer potential and the charge-up potential vary depending on the environment, the deterioration of the toner / transport member surface layer, and the like. Therefore, when developing in an actual developing region, an abnormal image such as excessive density or background smearing is likely to occur if development with a desired developing electric field cannot be performed.

  As shown in FIG. 10, by providing means for measuring the surface potential on the toner conveying member, that is, surface potential measuring means S, the potential on the surface of the conveying member can be measured one by one. Therefore, the result can be fed back to the second voltage applying means to obtain an appropriate developing electric field that does not generate an abnormal image.

In addition, by measuring the surface potential on the toner transport member while the toner is transported on the toner transport member, the charge of the toner layer generated by the transport toner cloud and the charge of the toner on the surface of the transport member is increased. The effective potential Vdev on the toner conveying member including the potential can be detected.
Therefore, the result can be fed back to the second voltage applying means, and an appropriate developing electric field that does not generate an abnormal image can be obtained with higher accuracy.

FIG. 11 shows the measured effective potential Vdev on the surface of the conveying member when n = 3 layers, Vhi = −60 V, Vlo = −260 V, tf = 5 kHz, voltage application duty 50%, toner q / m = −20 μC / g. It is an example of a result.
The second voltage applying means is turned on at point A, toner supply, that is, actual toner conveyance is started at point B, and the second voltage applying means is turned off at point C.
Between A and B, the measured values coincide with (−60−260) / 2 = −160 V, which can be calculated from Vhi = −60 V, Vlo = −260 V, and voltage application duty 50%.
In FIG. 11, −188 V is obtained by measuring the execution Vdev when the toner is being conveyed.
Further, the transport potential is unstable during the time immediately after the point B immediately after the start of toner transport. This is because toner conveyance is unstable immediately after the start of conveyance, and is not very suitable for use as a measured value of effective potential. Therefore, it is preferable that the time for measuring the surface potential on the toner conveying member is made variable so that the measurement value of the unstable time immediately after the start of conveyance is not used.

By the way, during toner conveyance, -188V, which is 22V lower than the calculated -160V, is the effective value Vdev, and the background potential generated by the background potential Vd of the electrostatic latent image carrier is compared with the calculated value. Therefore, 22V is smaller, and the margin for background dirt is reduced accordingly.
FIG. 12 shows an example of a flowchart for detecting and controlling the execution potential Vdev on the toner conveying member as one of the methods that can feed back the result (claim 4).
First, the toner is supplied and conveyed. First, a voltage is applied to the electrode of the toner conveying member 2 by the second voltage applying unit 12.
Thereafter, the developer carrier 3 is rotated at the same time as the voltage is applied to the developer carrier 3 by the first voltage application means 11.
When the voltage is applied to the developer carrying body 3 before the voltage is applied to the electrode of the toner carrying member 2 by the second voltage applying means 12, the toner carrying member 3 is rotated simultaneously with the rotation of the developer carrying body 3. The toner supplied to 2 is deposited and stuck in the supply area. Then, even if the transport electric field is applied thereafter, the transport electric field does not act much on the toner due to the charge of the toner itself, and the deposited toner does not move. The toner stuck and stuck also affects the subsequent supply of toner. Therefore, after the voltage is first applied to the electrode of the toner conveying member 2, the developer carrier 3 is rotated simultaneously with the voltage application to the developer carrier 3.
When the toner is transported while hopping on the toner transport member 2, the transport member surface potential Vdev during the next toner transport is detected. Vdev is an effective value on the toner conveying member 2 including the potential of the toner conveying member by the second voltage applying unit 12, the toner layer potential generated by the cloud of the conveying toner, and the charge-up potential that the toner charge is applied to the surface of the conveying member. It is a potential and serves as a developing bias for the toner carrying member facing the electrostatic latent image carrying member as well as the toner conveying member 2 in the developing region. Therefore, from the correlation between the background portion potential Vd and the exposure portion potential VL of the electrostatic latent image carrier set in advance, the Vdev is set so that an appropriate developing toner adhesion amount can be obtained without background contamination. The applied voltage is adjusted by feeding back to the two-voltage applying means 12.

For example, the values of Vhi and Vlo shown in FIG. 9 and the tf value can be adjusted.
The values of Vhi and Vlo directly change the conveying member potential by the second voltage applying means 12. However, since adjustment of (Vhi−Vlo) and tf are parameters that change the hopping energy of the toner, it is desirable that the value of (Vhi−Vlo) is not changed. Of course, a plurality of these parameters may be adjusted simultaneously.
This adjustment may be completed once, or Vdev is measured again after the adjustment, and the control is repeated until Vdev is within a desired range, for example, Vdev ≧ 50 + Vd (V).
If the control is repeated N times, it is considered that an abnormality has occurred and an abnormality is displayed on the display unit of the image forming apparatus.
Furthermore, when the image forming apparatus has a communication unit that communicates information with an external central management apparatus or the like, abnormality information may be transmitted to the central management apparatus or the like.
The upper limit N of the number of control repetitions may be a fixed value, or may be changed depending on the operation time of the image forming apparatus, the number of output sheets, and the like.
By providing the above-described toner conveying device in the developing device that is arranged to face the electrostatic latent image carrier 1 and that develops the electrostatic latent image on the electrostatic latent image carrier 1, it is effective in the developing device. The developing bias Vdev can be measured and adjusted.

  Further, as shown in FIG. 10, the surface potential measuring means S of the toner conveying member 2 is arranged downstream of the toner supplying means which is an area including the toner supply port 6 to the developer carrier 3 shown in FIG. By providing upstream of the position (development region) facing the electrostatic latent image carrier 1, the execution conveyance member surface potential Vdev in a state where the toner to be developed right now is conveying the toner conveyance member 2. Therefore, it is possible to perform feedback to the second voltage applying means 12 with higher accuracy (claim 7).

By incorporating the developing device having the above configuration into the image forming apparatus, it is possible to provide the advantages of the developing device as an image forming apparatus.
An example thereof will be described with reference to FIG.
The image forming apparatus includes an image carrier, a charging unit, a developing unit according to the present invention as a developing unit, and an image forming unit including a cleaning unit, black (K), magenta (M), cyan (C), and yellow. (Y) process cartridges 501K, 501M, 501C, and 501Y (hereinafter simply referred to as “process cartridge 501” when not distinguished from each other; the same applies to others), optical writing devices 502K, 502M, Transfer rollers 503Bk, 503Bm, 503Bc, and 503By facing the transfer belt 503A and the process cartridges 501K, 501M, 501C, and 501Y with the conveyance belt 503A interposed therebetween, the fixing device 504, the transfer belt 503A A sheet feeding device 505 that accommodates the material 506. .

  Here, the optical writing devices 502K, 502M, 502C, and 502Y are for writing a latent image on the charged image carrier of the process cartridge 501K, 501M, 501C, and 501Y according to the image information. Various devices such as a scanning device and an LED array can be used.

  The conveyance belt 503A is stretched between the conveyance roller 511, the driven roller 512, and the tension rollers 513 and 514, and rotates in the direction indicated by the arrow by the rotation of the conveyance roller 511. Then, an adsorption roller 515 for adsorbing the transfer material 506 onto the conveyance belt 503A is disposed opposite to the conveyance roller 511, and a toner image is formed on the conveyance belt 503A on the exit side of the conveyance belt 503A. A P sensor 516 for detecting a pattern is arranged.

The transfer rollers 503Bk, 503Bm, 503Bc, and 503By have at least a core metal and a conductive elastic layer that covers the core metal. The conductive elastic layer is an elastic material such as polyurethane rubber or ethylene-propylene-diene polyethylene (EPDM). In addition, an elastic roller in which a conductivity imparting agent such as carbon black, zinc oxide or tin oxide is blended and dispersed to adjust the electric resistance value (volume resistivity) to a medium resistance of 10 ⁶ to 10 ¹⁰ Ω · cm.
The fixing device 504 includes a heating roller 504a and a pressure roller 504b facing the heating roller 504a.
In this image forming apparatus, in a normal image forming operation, the transfer material 506 such as a recording sheet supplied from the paper supply device 505 is a transfer material that is a transfer body when a predetermined voltage is applied to the suction roller 515. It is adsorbed to the conveyance belt 503A.
The transfer material 506 moves together with the transfer material conveyance belt 503A while being carried on the transfer material conveyance belt 503A. During the movement, the toner images of the respective colors are sequentially transferred from the process cartridges 501K, 501M, 501C, and 501Y. A color toner image is formed thereon.
When the transfer material 506 passes through the conveyance belt 503A and reaches the fixing device 504, the toner image on the transfer material 506 is heated while being sandwiched between the heating roller 504a and the pressure roller 504b to be fixed on the transfer material 506. As a result, a visible image is fixedly formed on the transfer material 506.
Thereafter, the transfer material 506 on which the color image is formed is discharged to a paper discharge unit 507 at the top of the apparatus main body 510.

In a mode in which the color misregistration and toner density of each color toner image are adjusted, a toner image having a predetermined pattern is directly formed on the transfer material conveyance belt 503A from the image forming units 501K, 501M, 501C, and 501Y. The toner pattern is detected, and the writing timing and the development bias are changed based on the detection result, so that an optimum color image can be obtained.
The toner pattern on the transfer material conveyance belt 503A is adjusted in the charging polarity by the bias applied to the suction roller 515, and then processed by the process cartridges 501K, 501M, 501C, and the voltage applied to the transfer rollers 503Bk, 503Bm, 503Bc, 503By Collected at 501Y.

Next, the process cartridge 501 of the present invention will be described.
FIG. 14 is a schematic configuration diagram of a process cartridge.
The process cartridge 501 includes an image carrier 521, a contact charging member 531, the above-described developing device 541 (which may be another developing device), and a cleaning device 551.

The image carrier 521 is a negatively charged organic photoreceptor, and is provided so as to be rotated in the arrow direction (counterclockwise direction in the drawing) by a rotation driving mechanism (not shown).
The contact charging member 531 is a flexible charging roller in which a foamed urethane layer of medium resistance in which a urethane resin, carbon black as conductive particles, a sulfurizing agent, a foaming agent, etc. are formulated in a roller shape is formed on a core metal. is there.
The middle resistance layer formed on the core of the contact charging member (charging roller) 531 is not limited to the above urethane foam layer, but is urethane, ethylene-propylene-diene polyethylene (EPDM), butadiene acrylonitrile rubber. (NBR), a rubber material in which a conductive material such as carbon black or a metal oxide is dispersed for resistance adjustment in silicone rubber, isoprene rubber, or the like, or a foamed material thereof can be used.
The cleaning device 551 includes a cleaning blade 552 that is brought into contact with the rotation direction of the image carrier 521 in a counter direction, a waste toner storage unit 553 that stores the cleaned toner particles as waste toner, and the like.

Next, the operation of the process cartridge 501 will be described.
This is a multifunction machine that can function as a copier and a printer. When functioning as a copier, the image information read from the scanner is subjected to various image processing such as A / D conversion, MTF correction, and gradation processing. Is converted into write data.
When functioning as a printer, image information in a format such as a page description language or a bitmap transferred from a computer or the like is subjected to image processing and converted into write data.
Prior to image formation, the image carrier 521 starts rotating in the direction of the arrow in the figure, that is, in the counterclockwise direction so that the moving speed of the surface becomes a predetermined speed.
Further, the charging roller 531 is rotated with the image carrier 521.
At this time, a DC voltage of −200 V and an AC voltage of an amplitude of 1200 V and a frequency of 2 kHz are applied to the core of the charging roller 531 from the charging bias application power source, whereby the surface of the image carrier 521 is charged to about −200 V.
The optical writing device 502 irradiates the charged image carrier 521 with a laser beam 502a in accordance with the writing data.
That is, by changing the potential of the image portion by light irradiation, a difference from the potential of the non-image portion not irradiated with light is generated, and an electrostatic latent image is formed by this potential contrast.
The electrostatic latent image formed on the image carrier 521 by the optical writing device 502 is developed by the developing device 541 according to the present invention, and is visualized on the image carrier 521 as a toner image by adhering toner particles to the image portion. Is done.
The transfer material 506 is conveyed from the paper feeding device 505 in synchronization with the timing at which the toner image formed on the image carrier 521 arrives at the transfer portion that is the opposite portion between the transfer roller 503B and the image carrier 521. The toner image on the image carrier 521 is transferred to the transfer material 506 by the voltage applied to the transfer roller 503B. The transfer material 506 to which the toner image has been transferred is fixed by the fixing device 504, and a color image is output on the transfer material 506.
On the other hand, toner remaining on the image carrier 521 without being transferred (transfer residual toner) is cleaned by the cleaning device 551, and the surface of the image carrier 521 after cleaning is used for the next image formation.
The process cartridges 501K, 501M, 501C, and 501Y for forming these black, magenta, cyan, and yellow toner images are detachable from the image forming apparatus main body 510.
That is, the process cartridges 501K, 501M, 501C, and 501Y are detachable from the open space when the transfer material transport belt 503A is opened and retracted from the apparatus main body 510 as shown in FIG. It has an excellent configuration.
Of course, these may be detachably attached to the image forming apparatus as cartridges for each color.

1 is a schematic configuration diagram of an example of a developing device of the present invention. The schematic block diagram of other examples of the image development apparatus of this invention is shown. FIG. 4 is an explanatory cross-sectional view illustrating an enlarged part of a toner conveying member. A three-phase pulse drive waveform (voltage) of A phase, B phase, and C phase is shown. The toner movement state and the application state of the electrode of the toner conveying member are shown. (A)-(d) The movement state of a toner and the application state of the electrode of a toner conveyance member are shown. The schematic block diagram of an example of a power supply (2nd voltage application means) is shown. 3 shows a three-phase driving waveform of a transport voltage pattern in a transport region of a toner transport member. The + 100V or 0V application time ta and the repetition period tf of each phase for each electrode in the development region are shown. FIG. 2 is a schematic view on a toner conveying member constituting the toner conveying device of the present invention. An example of the result of measuring the effective potential Vdev on the surface of the conveying member under a predetermined condition is shown. An example of a flowchart of detection and control of an execution potential Vdev on the toner conveying member is shown. 1 is a schematic configuration diagram of an example of an image forming apparatus. It is a schematic block diagram of a process cartridge. 1 is a schematic configuration diagram of an example of an image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Latent image carrier 2 Toner conveyance member 3,13 Developer carrier 4,14 Developer accommodating part 5A, 5B, 15A, 15B Screw 6 Toner replenishment port 7 Developer layer control member 10 Developing device 11 First voltage application means 12 Second voltage applying means 20 Electrode 101 Support substrate 102 Electrode 103 Surface protective layer 103a Electrostatic transfer surface V11 to V13, V21 to V23 Drive voltage 104 Main body side power supply 501, 501K, 501M, 501C, 501Y Process cartridge 502K, 502M, 502C, 502Y Optical writing device 503A Conveying belt 503Bk, 503Bm, 503Bc, 503By Transfer roller 504 Fixing device 504a Heating roller 504b Pressure roller 505 Paper feeding device 506 Transfer material 507 Paper discharging unit 510 Device main body 511 Conveying roller 512 Followed roller 512
513,514 Tension roller 515 Adsorption roller 516 P sensor 516
521 Image carrier 531 Contact charging member (charging roller)
541 Developing device 551 Cleaning device 552 Cleaning blade 553 Waste toner storage unit

Claims (10)

A toner conveying device comprising a toner conveying member having a plurality of electrodes for generating an electric field for conveying and hopping toner by electrostatic force,
A toner conveying apparatus comprising surface potential measuring means for measuring a surface potential on the toner conveying member.   2. The toner transport according to claim 1, wherein at least when the toner is transported on the toner transport member, the surface potential on the toner transport member is measured by the surface potential measuring means. apparatus.   The toner conveying device according to claim 1, wherein the time for measuring the surface potential on the toner conveying member is variable.   4. The apparatus according to claim 1, further comprising a surface potential control unit configured to control a surface potential on the toner conveying member based on a measurement result obtained by the surface potential measurement unit. 5. Toner transport device.   The toner conveying apparatus according to claim 4, wherein the surface potential control unit on the toner conveying member is configured to change a voltage parameter applied to a plurality of electrodes. A developing device that is arranged to face an electrostatic latent image carrier and develops the electrostatic latent image on the electrostatic latent image carrier,
A developing device comprising the toner conveying device according to claim 1. A toner supply means for supplying toner to the toner conveying device;
The toner supplied by the toner supply means is transported to a position facing the electrostatic latent image carrier on the toner transport member, and the toner not used for development is transported on the toner transport member as it is. There,
The surface potential control means on the toner conveying member is provided downstream of the toner supply means and upstream of the position facing the electrostatic latent image carrier with respect to the toner conveying direction on the toner conveying member. The developing device according to claim 6.   An image forming apparatus comprising the developing device according to claim 6. At least one of a latent image carrier, charging means, and cleaning means in an electrophotographic process;
8. A process cartridge comprising the developing device according to claim 6 integrally held therein. An image forming apparatus comprising one or a plurality of process cartridges according to claim 9.

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