JPH0792622B2 - Electrostatic latent image developing device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrostatic latent image developing device used for developing an electrostatic latent image formed on the surface of an electrostatic latent image carrier in an electrophotographic process or the like, In particular, it relates to the toner density control means.

2. Description of the Related Art Generally, in this type of electrostatic latent image developing device that uses a two-component developer composed of a mixture of toner and magnetic carrier, a new toner corresponding to the amount of toner consumed by development is used. Need to be replenished.

Therefore, conventionally, various automatic toner concentration control devices have been provided. The main one is to detect the toner concentration of the developer in the developing device, compare this detected value with a reference value corresponding to a preset reference toner concentration, and if the former is lower than the latter, the toner The replenishing means is operated to replenish new toner.

For example, as described in Japanese Patent Publication No. 52-123242, a detection element is brought close to at least one surface of a developer which rotates in a developing device in a substantially strip shape, and toner is mixed without obstructing the flow of the developer. It is known that the ratio is detected as a change in magnetic permeability of the developer based on a change in the mixing ratio.

Problems to be Solved by the Invention By the way, when the concentration of the developer being conveyed is detected by, for example, a magnetic sensor, the mounting position of the sensor or the detection timing is important. This is because the developer is normally conveyed by the blade member, the sensor is installed around the blade member, and the density of the developer on the sensor constantly fluctuates due to the rotation of the blade member. This is because the toner density detection value also constantly changes. Therefore, if the toner density is detected at an arbitrary time point, the accurate toner density cannot be detected.

Means for Solving the Problems In order to solve the above problems, the electrostatic latent image developing device according to the present invention conveys (a) a developer including a mixture of toner and a magnetic carrier to a developing area. A developing means, (b) a developer conveying means having a stirring member for mixing and stirring the developer, (c) a toner replenishing means for replenishing new toner, and (d) a movement trajectory of the stirring member. (E) The toner concentration detecting means for the developer, which is installed in such a manner that (e) the toner concentration detecting means is set at fixed time intervals longer than the period in which the stirring member passes through the area facing the toner concentration detecting means. A control unit that extracts a peak value from the plurality of detected data, determines the toner concentration based on the peak value, and operates the toner replenishing unit based on the determination result. To collect.

Action That is, in the above-described configuration, the developer conveyed by the developer conveying means having the stirring member for mixing and stirring the developer is at the time when the developer is scraped to a constant thickness by the stirring member on the toner concentration detecting means. Detected as toner concentration, in other words,
The toner concentration of the developer is always detected in a constant and stable state, and the detected value is not affected by the fluctuation of the developer density due to the rotation of the stirring member.

Embodiment An embodiment of the electrostatic latent image developing device according to the present invention will be described below with reference to the accompanying drawings.

1 to 4, the electrostatic latent image developing device is
A developer circulating / conveying section (10) including a screw roller (12) and a bucket roller (16), and a toner accommodating section (40).
And a developing unit (60) having a developing sleeve (61) containing a magnetic roller (62), and each member is housed in a casing (1).

The developer circulating / conveying section (10) has a developer mixing / agitation conveying path (11) and a developer supplying / conveying path (15) formed by curving the bottom of the casing (1) downward. It is partitioned by a partition plate (2) rising from the bottom of 1), and openings (2a), (2b) at both ends of the partition plate (2)
And notches (2c), (2d) formed in the partition plate (2),
It is communicated by (2e). The conveying path (15) is parallel to the developing sleeve (61), and the conveying path (11) is arranged so as to be lower than the conveying path (15) on the front side in FIG. The opening (2a) is continuous with the inclined surface (3). The inclined surface (3) has an angle of repose of the developer or more so that the developer can easily flow.

The developer used in this embodiment is a so-called two-component magnetic developer composed of a mixture of magnetic carrier and non-magnetic toner.

The screw roller (12) is an apparently spiral blade plate (14) attached to the support shaft (13), and can be rotationally driven in the direction of arrow (a) with the same inclination angle in the transport path (11). It is installed in. The screw roller (12) has a function of mixing and stirring the developer while conveying the developer in the direction of the arrow (A) based on the rotation in the direction of the arrow (a), and the blade plate (14) is cut out by about half. Is for sufficiently exerting the mixing and stirring action.

The developer supply / conveyance path (15) is provided at a position lower than the developing sleeve (61) and parallel to the developing sleeve (61), and the magnetic concentration type toner concentration sensor (25) described in detail below is provided. is set up.

The bucket roller (16) is a hexagonal support plate (18),
Bridging the bucket (19) to each side of (18), the bucket (1
The blade plate (20) is attached to the inside of 9), and it rotates in the direction of arrow (b) into the conveying path (15) through the support shaft (17) penetrating the inside of the hugget roller (16). It is installed so that it can be driven. The bottom of the bucket (19) is opened at equal intervals, leaving small pieces (19a), to increase the freedom of movement of the developer. Further, the bottom portion (19b) on the front side is left to enhance the circumferential conveying force of the developer. The vane plate (20) is provided with a plurality of vane portions twisted at an angle of 15 ° on the outside of the ring portion, and the small protrusions of the vane portions are used as small pieces (19a) of the bucket (19).
It is fixed by fitting to. The bucket roller (16) scoops the developer by the side piece of the bucket (19) based on the rotation in the direction of the arrow (b) and supplies the developer to the outer peripheral surface of the developing sleeve (61), and at the same time, the blade plate (20). Has a function of carrying in the direction of the arrow (B). The vane plate (20) has not only a developer transport function but also a strength reinforcing function for the hugget (19), and prevents the bucket (19) from warping.

In the above configuration, the developer is the rotation of the screw roller (12) in the direction of the arrow (a), and the bucket roller (16).
Based on the rotation in the arrow (b) direction, the paper is conveyed in the arrow (A) direction in the conveyance path (11), in the conveyance path (15) in the arrow (B) direction, and in the arrow (A) direction. The developer that has reached the downstream end of the transport path (11) is guided to the inclined surface (3) from the opening (2a) and moves to the transport path (15).
In addition, a part of the developer being transported through the transport path (11) flows into the transport path (15) through the notches (2c), (2d) and (2e). On the other hand, the developer transported in the direction of the arrow (B) and reaching the downstream end of the transport path (15) has the bottom portion (19) of the bucket (19).
It is scooped up in b), moves from the opening (2b) to the transport path (11), and is circulated and transported through the transport paths (11) and (15). In this case, the transport level at the downstream end of each transport path (11), (15) in the transport direction is set higher than the upstream transport level of the other transport path (15), (11). The agent does not stay at the downstream end of each of the transfer paths (11), (15) and smoothly flows from the openings (2a), (2b) to the other transfer path (15),
There is no deviation of the developer particularly in the developer supply / conveyance path (15) after moving to (11).

Further, the developer is transported in the transport path (15) in the direction of the arrow (B), and part of it is scooped up by the bucket (19) and supplied to the outer peripheral surface of the developing sleeve (61). The supply here is uniform in the axial direction of the developing sleeve (61) because the developer is not biased in the conveying path (15).

By the way, notches (2c), (2d),
The reason why (2e) is formed and the developer is moved to the conveying path (15) in the middle of the conveying path (11) is as follows.

That is, the developer transported through the transport path (15) is used for the development and the toner is consumed as described above. If the notch is not present, the developer simply circulates in the transport paths (11) and (15), but in this case, the developer is transported in the transport path (15).
Even if the toner has a standard toner density on the upstream side, the toner density becomes lower than the standard on the downstream side. Notch (2
c), (2d), and (2e) are for eliminating such problems. In this embodiment, a notch (2c), (2d), (2e) having a width of 10 mm is formed at three locations on a partition plate (2) having a length of 280 mm. As a result, variations in toner concentration in the longitudinal direction of the transport path (15) are eliminated, the circulation efficiency of the developer is improved, and the toner concentration is stabilized.

Further, new toner is replenished from the toner storage section (40) to the upstream side of the conveyance path (11) by the toner replenishing means described below, and the arrow (A) is supplied in the conveyance path (11) together with the existing developer. While being conveyed in the same direction, they are mixed and stirred and sufficiently charged.

The toner storage section (40) is provided with a stirring member (42), an empty detection plate (46), and a replenishment inside a toner hopper (41) partitioned by walls (4a) and (4b) behind the transport path (11). A toner cartridge (55) in which a roller (51) is provided, and replenishment toner is pre-filled in the upper part of the toner hopper (41).
Is detachably attached to the toner cartridge (55).
The toner for replenishment is replenished in the hopper (41) by sliding the bottom plate (56) of the. Stirrer (4
2) is attached to both ends of the support shaft (43) via plate members (44), and can be rotated in the direction of arrow (c) with the support shaft (43) as a fulcrum. A) To prevent the cross-linking phenomenon and blocking of the toner. The supply roller (51) is formed by spirally winding the conveying blade (53) around the support shaft (52) and rotationally driven in the direction of the arrow (d) on the supply path (49) located at the bottom of the hopper (41). It is installed as possible. Further, the front side of the replenishing path (49) is continuous with the conveying path (11) at the toner replenishing inclined surface (50). The inclined surface (50) is set at an angle of repose of the toner or more so that the toner can easily flow. That is, the toner in the hopper (41) is conveyed in the direction of the arrow (D) through the replenishment path (49) based on the rotation of the replenishment roller (51) in the direction of the arrow (d), and from the front side to the inclined surface (50). It is guided and supplied to the upstream side (P) (see FIG. 4) of the transport path (11). The rotation time of the toner replenishing roller (51) is determined by comparing the toner concentration detection value in the developer in the conveyance path (15) by the toner concentration sensor (25) with the reference value by the control circuit described below. It is controlled by turning on and off the supply motor (73) (see FIG. 6).

On the other hand, the empty detection plate (46) is swingable in the vertical direction along both inner side surfaces of the hopper (41) about the pin (47) as a fulcrum, and a resistance plate (48) is attached to the tip. Further, a magnet is fixed to an empty detection plate (not shown) on the front side in FIG. 1, and a reed switch that is turned on / off by the contact / separation of the magnet is installed on the inner surface facing each other. The empty detection plate (46) engages with the stirring member (42) and moves upward in accordance with the upward rotation of the stirring member (42). When the engagement is released, the empty detection plate (46) moves downward by its own weight. That is,
The empty detection plate (46) repeatedly moves up and down for each rotation of the stirring member (42), and when it moves down, the resistance plate (48) receives resistance due to the toner in the hopper (41), and the degree of resistance is 41) Proportional to the amount of toner in Hoppers (41)
As the amount of toner inside the empty detection plate (46) decreases, the lower position of the empty detection plate (46) lowers. When the toner becomes empty, the magnet provided on the empty detection plate (46) activates the reed switch, and Toner empty is displayed on the operation panel.

The developing portion (60) is provided with a developing sleeve (61) having a magnetic roller (62) built-in between the arcuate portion (5) of the casing (1) and the dust and smoke prevention plate (7). ), The tip of the spike height regulating plate (63) is made to oppose. The developing sleeve (61) is formed of a non-magnetic conductive material (for example, aluminum) in a cylindrical shape, has fine irregularities formed on the outer peripheral surface by sandblasting, and can be rotationally driven in the direction of arrow (e). It faces the surface of the photoconductor drum (100) that can be driven to rotate in the direction of the arrow (f).

The magnetic roller (62) has magnetic poles (N ₁ ) to (N ₅ ),
(S ₁₎ ~ a (S _6), the magnetic pole (S _3), and is fixed to (S ₄₎ is obtained by magnetizing As identical poles adjacent, the developing sleeve (61) inside. This magnetic roller (62) has the same pole (S ₃ ),
The magnetic force of (S ₄ ) is weakly magnetized.

The head height regulating plate (63) has its tip facing between the magnetic poles (N ₄ ) and (S ₄ ), and is installed at an angle of 60 ° from the horizontal plane.

On the other hand, the end portion of the casing (1) rises immediately below the developing area (Y) to serve as a spill prevention plate (6) for dust and toner, and the tip of the spill prevention plate (6) has a magnetic pole (S ₁ ). It is located in the part facing. In other words, the magnetic pole (S ₁ ) is located on the straight line connecting the tip of the anti-spill plate (6) and the center of the developing sleeve (61).

In the developing section (60) having the above-mentioned configuration, the developer is bound by the magnetic force of the magnetic roller (62) and the developing sleeve (61).
Is held on the outer peripheral surface of the developing sleeve (61), and is conveyed in the arrow (e) direction on the outer peripheral surface of the developing sleeve (61) based on the rotation of the developing sleeve (61) in the arrow (e) direction. The electrostatic latent image formed on the surface of (100) is developed. The amount of conveyance is regulated by cutting the height of the gap when passing through the height control plate (63). Also,
The new developer is the arrow (b) of the bucket roller (19).
It is supplied to the portion on the outer peripheral surface of the developing sleeve (61) that faces the magnetic poles (N ₃ ) and (S ₃ ) based on the rotation in the direction. Here, the developer is separated from the outer peripheral surface of the developing sleeve (61) by the repulsive magnetic field between the auxiliary magnetic poles (S ₃ ) and (S ₄ ), and collides with the spike height regulating plate (63) at the front part thereof. The developer is mixed and stirred with the convective developer, and the fresh developer is cut off by the spike height regulating plate (63) and conveyed to the developing area (Y).

In the developing operation described above, the toner density of the developer transported through the developer supply transport path (15) is detected by the toner density sensor (25) on the downstream side of the transport path (15). Then, when it is determined that the detected toner density is lower than the reference toner density, and the density detection value tends to decrease, the toner replenishing roller (51) is rotated to newly replenish the toner, and the toner is replenished. .

Next, the mechanism and control method for performing the above toner density control will be described in detail.

As shown in FIG. 5, the toner concentration sensor (25) is obtained by fitting a coil (25a) into a core (25b) made of a magnetic material and covering the cover (25c) with the cover (25c) as a developer. It is installed facing toward and detects a change in toner concentration as a change in magnetic permeability of the developer. In this sensor (25), the outer diameter of the coil (25a) is proportional to the outer diameter of the core (25b), and the larger the outer diameter, the larger the change in inductance that can be detected as the output change. A characteristic of this type of sensor (25) is the detection depth corresponding to the outer diameter of the core (25b), and in order to stabilize the output, the thickness of the developer at the detection section is set to the core (25b).
It is desirable that the radius be equal to or larger than the radius of b). The bucket roller (16) supplies the developer to the developing sleeve (61) based on the rotation in the direction of the arrow (b), and also supplies the developer onto the sensor (25) so that the required thickness of the developer is obtained. Secure.

Instead of covering the cover (25c), the coil (25a) and the core (25b) may be resin-molded.

By the way, in this embodiment, as shown in FIG. 2, the toner concentration sensor (25) faces the bucket tip locus of the bucket roller (16) and is set at an interval of 2 mm. The transport amount of the developer on the toner concentration sensor (25) by the bucket (19) varies depending on whether the bucket (19) passes or not. In other words, the developer density on the sensor (25) fluctuates at regular intervals depending on the presence / absence of pressure by the bucket (19). If this fluctuation is detected by the sensor (25) for a little long time without toner consumption,
It is determined that the detection value when the bucket (19) passes over the sensor (25) indicates the peak value. At the time of detecting this peak value, the developer on the sensor (25) is accurately scraped by the bucket (19) to a thickness of 2 mm, and the density of the developer at this time is the highest and stable. Therefore, in the present invention, the detection value at the time when the thickness of the developer on the sensor (25) is rubbed off by the bucket (19) is used as the toner concentration for the toner replenishment control. That is, if the toner density is detected by capturing the timing showing the peak value, the developer is detected in the most stable state on the sensor (25). However, from the opposite viewpoint, if the peak value is obtained, the toner density can be detected in such a stable state. As described in detail below, in this embodiment, the toner value is accurately detected by obtaining the peak value.

The toner concentration sensor (25) is a coil (25a).
When the bucket roller (16) made of non-magnetic conductive material such as aluminum passes over the sensor (25), the inductance will be affected and the detected value will fluctuate. To do. Therefore,
The value detected by the toner concentration sensor (25) must be understood as considering the effect of the bucket roller (16).

As shown in FIG. 6, the control circuit is mainly composed of a microcomputer (70) and has a toner density sensor (25).
Outputs the signal from the oscillator (26) to the detector (27) as a change in magnetic permeability in the developer, and the analog signal from the detector (27) is input to the analog input port of the microcomputer (70). It The output port of the microcomputer (70) is connected to the toner replenishing stepping motor (73), the main motor (74), and the photosensitive drum motor (75), respectively. The toner supply motor (73) rotationally drives the toner supply roller (51) and the stirring member (42), and the main motor (74) rotationally drives the developing sleeve (61), the screw roller (12), and the bucket roller (16). Then, the photosensitive drum motor (75) rotationally drives the photosensitive drum (100). Further, the input / output port of the microcomputer (70) is connected to the battery backup RAM (7
7) connected to.

The output data from the detector (27) of the toner concentration sensor (25) is an analog signal, so after inputting it to the analog port of the microcomputer (70) and converting it to a digital signal using an A / D converter. , Data processing is performed.

In the above control circuit, the peak value of the output voltage of the detector (27) is inversely proportional to the toner concentration of the developer on the sensor (25), and its characteristic is as shown by the characteristic curve (Q) in FIG. . Then, the peak value of the output voltage of the detector (27) is digitally converted into the toner concentration by the microcomputer (70), and the reference value of the toner concentration stored in the RAM (77) in advance (corresponding to the toner concentration of 8 wt%). Compared with the latter, when the former is higher than the latter and the toner concentration detection value is decreasing, a replenishment stepping motor (73) for a certain number of pulses
Is rotated to supply a fixed amount of new toner to the replenishing portion (P) (see FIG. 4).

By the way, the bucket roller (16) is
It is rotated at 190 rpm and has 6 buckets (19) attached. Therefore, the bucket (19) passes over the toner density sensor (25) 19 times in 1 second, and 52.6 msec (1 sec / 1 sec.
The detected value shows the peak value every 9). The microcomputer (70) outputs the peak value of the output of the detector (27) as sampling peak value data (V TEMP) every second as a concentration control signal per unit time. That is, the output of the detector (27) for 1 second is set to 1 of the microcomputer (70).
Routine cycle time is extracted every 5 msec, and the value is taken in as sampling data (V MOM),
This sampling data (V MOM) and peak value data (V
TEMP) and the larger value is the peak value data (V
Repeatedly rewriting as TEMP) for 1 second (2
The detected peak value (which may be seconds) is finally output as a value for controlling the toner density, and is compared with the reference value (V STAN). That is, since the rewriting is the sampling data (V MOM = 0) and the peak value data (V TEMP = 0) at the beginning, the value of the first sampling data (V MOM) becomes the peak value data (V TEMP), The next sampling data (V MOM) is compared with the peak value data (V TEMP) and the larger value is set as (V TEMP). In this embodiment, this process is repeated 200 times in 1 second.

Next, the toner replenishment control will be specifically described.

First, the toner supply capacity of the toner supply roller (51) is 1g /
It is set to rotate. On the other hand, the stepping motor (7
3) uses a resolution of 1/48, and 1 by gear means
Decelerate to / 10 and rotate the supply roller (51). Therefore, the replenishing roller (51) has a rotation speed of 12 rpm and a rotation angle resolution of 1/480. Therefore, the stepping motor (7
It is designed to replenish 2.1 mg (1 g / 480) of toner per 1 pulse rotation of 3).

On the other hand, when the toner concentration sensor (25) is provided near the notch (2c) as in this embodiment (see FIG. 4), the developer is conveyed from the toner replenishment section (P) to the magnetic sensor (25). The distance of the road is 70 mm. Also, the developer transfer capacity of the screw roller (12) is 2.33 g / sec in the measured value, and the transfer speed is 5 mm / s.
ec. Therefore, there is a time delay of 14 seconds for the developer to be conveyed onto the toner concentration sensor (25) after the toner replenishing operation is performed.

The toner density detection interval is the time required for one copy when continuously copying A4, which is the standard size,
The toner replenishment amount per one time is set to the toner amount required for copying a document having a darker density than the standard density of A4 which is the standard size (7 to 8% in black and white ratio). That is, the toner consumption in the developing process is, for example, 60 A4 size copy papers / m.
When copying with in, assuming that the dark original is a black-and-white ratio of 15 to 20%, it can be considered that the maximum is 11 g / min.
That is, 183 mg (11g / 60se)
c) Stepping motor (7
3) can be rotated. Therefore, the number of rotation steps (N) of the stepping motor (73) during toner supply is 87.
It is a step (183mg / 2.1mg), and a fixed amount of 183mg is supplied.

By the way, if the toner concentration of the developer on the conveyance path (15) is lowered by the developing operation and the detected toner concentration is not lower than the reference toner concentration, the toner replenishing operation is performed, and this embodiment is modeled. In this case, it takes about 14 seconds from the toner replenishing section (P) to the sensor (25) for the developer to feed back to the toner concentration sensor (25) that the toner concentration starts to rise. 15)
As shown in FIG. 8, the toner concentration of the developer changes around the reference toner concentration (8 wt%, see line L ₁ ). That is, if the detected toner concentration becomes equal to or lower than the reference toner concentration, the toner replenishment flag is set to "0" to start the toner replenishment operation, and after 14 seconds, the replenishment toner is conveyed to the installation position of the sensor (25). The detected concentration value begins to rise. However, if toner replenishment is continued until the detected toner concentration detection value reaches the reference toner concentration after 14 seconds, excessive replenishment occurs and the toner concentration exceeds 9 wt% (see line L ₂ ) and over toner is detected. turn into. If the toner is over-toner, the toner and the carrier are not in a proper mixed state, so that the toner is less likely to be triboelectrically charged, which causes problems such as background fogging of the toner on the copy paper and spilling of the toner outside the developing device.

Such overtoner is generated by supplying the replenishment toner for 8 seconds until it reaches the reference toner concentration even after the replenishment toner is conveyed to the installation position of the sensor (25) and the detection value of the toner concentration starts rising as described above. Substantially 1.46 g (183 mg ×
This is because the toner of 8) was replenished.

Therefore, in the automatic toner concentration control according to the present embodiment, control is performed to stop the toner replenishing operation when the toner concentration detected by the replenishment toner tends to increase even if the detected toner concentration is equal to or lower than the reference toner concentration. .
As a result, excessive replenishment of toner is prevented, and as shown in FIG. 9, overtoner in which the toner concentration becomes 9 wt% or more is prevented, and the toner concentration fluctuation cycle is about the same as that of the control method of FIG. It becomes 1/2, and the toner density control becomes more accurate.

Next, a specific processing procedure for toner supply will be described with reference to the flowchart in FIG.

When the power is turned on, first, in step (S1), the program of the microcomputer (70) is set to the initial state, and at the same time, the timer (T ₁ ) for controlling the sampling timing of toner concentration detection is set to 1 second, and the toner concentration is set. The sampling data (V MOM), the sampling peak value data (V TEMP) and the hold value data (V BEF) are reset to “0” and the toner supply flag is set to “1”. Then, in step (S2), the 1-routine timer is set. This is because the processing of this main routine is executed at every set time (5 msec in this embodiment).
Subsequently, an input / output process is executed in step (S3). That is, it inputs and outputs various measuring instruments connected to the microcomputer (70), external information, and various load states.

Next, in step (S4), it is established whether or not the timer (T ₁ ) has expired. If not completed (NO), in step (S5)
The detection signal from the detector (27) every 5 msec is A / D converted to obtain sampling data (V MOM) of a digital signal.
Then, in step (S6), sampling data (V MO
M) and peak value data (V TEMP) are compared, and if the former is larger than the latter (YES), the value of peak value data (V TEMP) is sampled data (V MOM) in step (S7).
To the value of.

On the other hand, when the timer (T ₁ ) expires, [Step (S4)
YES], the timer (T ₁ ) is set to 1 second again in step (S8), and then the toner supply is determined in the following steps. That is, in step (S9), the sampling peak value data (V TEMP) is compared with the reference value data (V STAN) corresponding to the reference toner density. If the former is larger than the latter, it means that the toner density is insufficient, and in step (S10), the sampling peak value data (V TEMP) here is compared with the hold value data (V BEF) detected one second before. To do. If the former is larger than the latter (NO), the toner density tends to increase, so it is necessary to avoid over-toner, and toner is not replenished, and step (S12) is performed.
Move to. Data (V TEMP) rather than data (V BEF)
If is larger (YES), the toner density tends to decrease, so that the toner replenishment flag is set to "0" in step (S11) to enable toner replenishment.

Next, in step (S12), the value of hold value data (V BEF) is rewritten to sampling peak value data (V TEMP), and in step (S13) sampling peak value data (V TEMP)
TEMP) to "0". And step (S
After confirming that the main motor (74) is turned on in 14), it is determined in step (S15) whether the toner supply flag is "0". When replenishing the toner, it is confirmed that the main motor (74) is turned on because the screw roller (12), the bucket roller (16) and the like of the developing device are rotationally driven by the main motor (74). This is because the supplied toner and the developer are mixed and stirred only when the ON state is turned on. If YES in step (S15), that is, if the toner is to be replenished, the number of rotation steps (R) of the toner replenishing stepping motor (73) is set to (N) in step (S16).
In this embodiment, the quantitative supply method is adopted, and the number of steps (N) set here is "87" as described above. Then, in step (S17), the toner supply flag is set to "1" to prepare for the next supply amount setting operation.

Next, in step (S18), it is determined whether or not the number of steps (R) is "0", and if "NO", the toner supply motor (73) is rotated by one step in step (S19), and then step (S20). ), The number of steps (R) is decremented by "1", other processing is performed in step (S21), and in step (S22), the one-routine timer is awaited and the process returns to step (S2).

In the steps (S19) and (S20), it is confirmed that the step number (R) of the motor (73) is subtracted to "0" in the step (S18), that is, a predetermined amount (183 mg) of toner is stored. Continue until replenished.

EFFECTS OF THE INVENTION As is apparent from the above description, according to the present invention, the thickness of the developer on the toner concentration detecting means is rubbed off by the developer carrying means having the stirring member for mixing and stirring the developer. Since the toner density at the time point is detected, the toner density is detected in a constant and stable state of the developer, and the detected value is affected by the fluctuation of the developer density due to the rotation of the stirring member. It is possible to accurately control the toner density.

[Brief description of drawings]

The drawings show one embodiment of the electrostatic latent image developing device according to the present invention. FIG. 1 is a perspective view showing the entire internal structure, FIG. 2 is a sectional view of the front side thereof, and FIG. Sectional view at 4th
The figure is a schematic sectional view in a horizontal plane. 5 is an exploded perspective view of the toner concentration sensor, FIG. 6 is a block diagram of a control circuit,
FIG. 7 is a graph showing the characteristics of the sensor, FIGS.
FIG. 10 is a graph showing a change in toner density based on toner replenishment control, and FIG. 10 is a flowchart showing a processing procedure. (10) …… Developer circulation transport section, (12) …… Screw roller, (16) …… Bucket roller, (19) …… Bucket, (25) …… Toner density sensor, (40) …… Toner storage Section, (51) ... toner supply roller, (60) ... development section, (61) ... development sleeve, (70) ... microcomputer, (73) ... toner supply stepping motor, (74) ... ... Main motor, (P) ... Toner supply unit, (Y) ... Development area.

Claims (1)

[Claims] 1. A developing means for feeding a developer comprising a mixture of toner and a magnetic carrier to a developing area, a developer feeding means having a stirring member for mixing and stirring the developer, and replenishing new toner. Toner replenishing means, developer toner concentration detecting means installed so as to face the movement path of the stirring member, and a constant time longer than the cycle in which the stirring member passes through the area facing the toner concentration detecting means. For each time, a peak value is extracted from a plurality of data detected by the toner concentration detecting means, the toner concentration is determined based on the peak value, and the toner replenishing means is operated based on the determination result. An electrostatic latent image developing device comprising: