JPH03174568A - Developing method - Google Patents

Abstract

PURPOSE:To maintain developing characteristic satisfactorily by measuring the surface potential of the developing area of a toner holding body, and adjusting and controlling a bias voltage applied to a toner refilling member to keep the surface potential of the toner holding body constant. CONSTITUTION:The surface potential of a developing roller 3 including a toner layer is measured with the probe 7a of a surface electrometer 7, and it is applied to a toner refilling roller 5 after an appropriate bias for toner refilling corresponding to the above measurement is adjusted, thereby, the surface potential of the developing area of the developing roller 3 can be kept constant. In such a way, even when a dielectric layer and a resistance layer 3C are provided at the toner holding body 3, so-called developing potential can be kept constant, which maintains the developing characteristic satisfactorily without generating the fluctuation of the developing characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing method in which toner is supplied to an electrostatic latent image formed on a latent image carrier for development.

[Prior Art] Generally, in various image forming apparatuses such as copying machines, printers, and facsimile machines, an electrostatic latent image corresponding to an image is formed on a latent image carrier such as a photoreceptor, and this electrostatic latent image For example, a one-component developer is supplied from a toner carrier provided in a developing device to perform development.
This allows a visible image to be obtained.

The toner carrier that conveys such a one-component developer (hereinafter simply referred to as toner) is formed in the shape of a roller, and is cyclically conveyed at a predetermined period while holding the toner on its surface in a developing area. A predetermined developing process is executed. That is, for the toner carrier, a toner replenishment member similarly formed in the shape of a roller or the like is attached in contact with a developer replenishment area, and a developer replenishment member formed downstream of the developer replenishment area is attached. A toner thinning regulating means formed in the form of a blade or roller is attached in contact with the developer thinning region, and first, in the developer replenishment region, the new toner stored in the toner storage section is The toner carrier is replenished by the action of the replenishing member, and the toner is thereby deposited on the surface of the toner carrier. Further, the toner deposited on the surface of the toner carrier is uniformly thinned in the developer thinning region by the leveling action of the toner thinning regulating means. This uniform thin toner layer is sent to a development area formed downstream of the developer thinning area, where the toner is selectively supplied to the electrostatic latent image and a developing operation is performed. It is now possible to

On the other hand, when the toner carrier is formed from a conductive member, an excessive amount of toner adheres to a solid image compared to a line image, and a good image tends to be difficult to obtain. To solve this problem, the conductive member of the toner carrier is covered with a dielectric layer, a resistor layer, or an insulating layer, thereby weakening the developing electric field in the solid image area (the electric field acting on the toner in the developing area). Various attempts have been made in the past.

[Problem to be solved by the invention] However, in this way, there is a dielectric layer on the toner carrier.

When a resistor layer or an insulating layer is provided, the uneven thickness of the dielectric layer, resistor layer, or insulating layer itself may cause charge accumulation on the surface of the toner carrier or variation in the amount of charge on the toner particles. There is a problem in that the surface potential of the body changes and the development characteristics change. Furthermore, variations in the surface potential of the toner carrier are also caused by bias voltages applied to each member that is in contact with the toner carrier.

1, for example, JP-A-54-112635 or JP-A-54-115, which deals with changes in development characteristics.
There is a method described in Publication No. 250 and the like. These conventional means measure the potential of the toner layer on the toner carrier and the potential of the surface of the photoreceptor, and perform control to maintain a constant relationship between the two. However, when a dielectric layer, a resistor layer, or an insulating layer is provided on the toner carrier as described above, this method cannot be adopted because the toner layer potential itself cannot be directly measured.

Therefore, the present invention is capable of preventing the above-mentioned fluctuations in development characteristics and maintaining good development characteristics even when a dielectric layer, a resistor layer, or an insulating layer is provided on a toner carrier. The purpose of the present invention is to provide a developing method that enables the following.

[Means for Solving the Problem] In order to achieve the above object, the invention described in claim 1 supplies toner to the toner carrier from a toner supply member under a predetermined bias voltage, and In a developing method in which a toner carrying member is cyclically conveyed while holding toner on the surface of a body, and a developing step is executed in a developing area, the surface potential of the toner carrying member in the developing area is measured, and the toner carrying member is The toner replenishing member is configured to adjust and control the bias voltage applied to the toner replenishing member so that the surface potential of the body is maintained constant.

Further, the invention described in claim 2 is such that the toner held on the surface of the toner carrier is made into a thin layer by a toner regulating member under a predetermined bias voltage, and the toner is deposited on the surface of the toner carrier. In a developing method in which a toner carrier is cycled while maintaining a thin layer and a developing step is executed in a development area, the surface potential of the toner carrier in the development area is measured, and the surface potential of the toner carrier is measured. The bias voltage applied to the toner regulating member is adjusted and controlled so that the toner regulating member is maintained constant.

[Function] In the means having the structure described in claim 1, the surface potential of the toner carrier containing the toner layer sent to the development area is measured, and an appropriate bias for toner replenishment corresponding to the surface potential is measured. is applied to the toner replenishing member after adjustment, so that the surface potential in the development area of the toner carrier is maintained constant.

Furthermore, in the means having the structure described in claim 2, the surface potential of the toner carrier containing the toner layer sent to the development area is measured, and an appropriate bias for regulating the toner is adjusted accordingly. The voltage is then applied to the toner regulating member, whereby the surface potential in the development area of the toner carrier is maintained constant.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

First, an example of a developing device for carrying out the present invention will be explained with reference to FIG. A developing roller 3 serving as a toner carrier is pivotally supported within the developing casing 2 of the developing device 11.
This developing roller 3 is connected to the photosensitive drum 4 in the developing area.
is arranged so as to be in elastic contact with the surface of the The photosensitive drum 4 and the developing roller 3 are rotated in opposite directions as shown by arrows A and B, that is, in the same direction at the contact area between the two, and the developing roller 3 where the developing operation is performed is located at the contact area between the two. A region is formed as described above.

In the developing roller 3, as particularly shown in FIG. 2, a conductive elastic body of a predetermined thickness made of silicone rubber mixed with carbon is surrounded by a support 3a formed of a conductive core metal. N3b is attached, and a high-resistance conductive particle-dispersed resin layer 3G of a predetermined thickness made of silicone resin mixed with a small amount of carbon is further adhered on the conductive elastic layer 3b. . By providing the conductive elastic layer 3b, the photoreceptor drum 4
The electric field strength in the developing area is appropriately controlled by providing the high resistance conductive particle dispersed resin layer 3c. A predetermined developing bias voltage is applied to the support 3a of the developing roller 3 from the bias power supply circuit 14.

The developing casing 2 is provided with a portion of a toner hopper as a toner storage section, and a toner replenishing member that replenishes the surface of the developing roller 3 with new toner (negatively charged toner) stored in the toner hopper. A toner replenishing roller 5 is pivotally supported within the developing casing 2 so as to be rotationally driven in the direction shown by arrow C.

The toner replenishment roller 5 is formed of a roller member made of urethane foam, and is arranged so as to be in contact with the surface of the developing roller 3, and a developer replenishment area is formed in the contact portion.

Further, a predetermined toner supply bias voltage is applied to the toner supply roller 5 from a bias power supply circuit which will be described later. The toner on the toner supply roller 5 is
The toner is supplied to the surface of the developing roller 3 based on the relative potential difference between the toner supply bias voltage and the developing bias voltage.

Further, in the downstream region of the toner supply roller 5 in the rotational direction of the developing roller 3, a toner layer regulating blade 6 is arranged as a toner regulating member that forms a thin layer of toner supplied to the surface of the developing roller 3. . The leading edge of the toner layer regulating blade 6 is arranged so as to be in uniform contact with the surface of the developing roller 3 in the axial direction, and a developer thinning region is formed in the contact area. There is.

Furthermore, in an area downstream of the developing area in the rotational direction of the developing roller 3 and upstream of the toner replenishing roller 5, there is a device for measuring the surface potential of the developing roller 3 after the developing operation is performed. A probe 7a of a surface electrometer 7 is provided. The probe 7a of this surface electrometer 7 is arranged close to the surface of the developing roller 3.

The detection output from the surface electrometer 7 is passed through the arithmetic circuit 8 to the first
The signal is sent to the differential circuit 9. The voltage value of the developing bias applied to the developing roller 3 from the power supply circuit 14 is input to the first difference circuit 9, and the surface electrometer 7
The first difference circuit 9 calculates the difference between the surface potential measurement value of the developing roller 3 detected by and the voltage value of the developing bias actually applied, that is, the difference potential.

The arithmetic circuit 8 is provided with an integral circuit, and the surface potential measurement value of the developing roller 3 measured during a certain period of time is sampled and smoothed by this integral circuit. This smoothed value is
is output to the first difference circuit 9 as a surface potential measurement value.

Furthermore, the deviation signal output from the first difference circuit 9 is transmitted to a delay circuit 11 formed from a delay element such as a COD.
is applied to. This delay circuit 11 has the function of delaying the output from the first difference circuit 9 by the travel time t from the potential measurement position to the toner replenishment area and sending it to the second difference circuit 12. In the second difference circuit 12, the first
The deviation which is the output of the difference circuit 9 is subtracted from the output value from the reference bias power supply 13, and this is applied to the toner replenishment roller 5 as the final toner replenishment bias voltage.

In such an example of an apparatus, first, exposure writing is performed on the surface of the photoreceptor drum 4, which is charged in a negative manner, to form an electrostatic latent image corresponding to an image. Toner is selectively supplied to this electrostatic latent image from the JJ2 image roller 3 of the developing device 1 in the development region according to the contrast of the latent image, thereby developing the electrostatic latent image and forming a toner visible image. is obtained. Further, new toner in the toner hopper is supplied to the developing roller 3 by the toner replenishing roller 5 under a predetermined toner replenishing bias voltage in the developer replenishing area, and the new toner is deposited on the surface of the developing roller 3. The toner is uniformly formed into a single layer by a toner layer regulating blade 6 in the developer aN region and sent to the development region.

An example of the developing method of the present invention using the above-mentioned apparatus example will be specifically described.

First, the surface potential of the developing roller 3 including the toner layer is measured by the probe 7a of the surface electrometer 7, and a corresponding appropriate toner replenishment bias is applied to the toner replenishment roller 5 as follows.

For example, due to contact between the toner supply roller 5 and the developing roller 3 or contact between the photosensitive drum 4 and the developing roller 3, the surface layer of the developing roller 3 is charged, and the third
As shown in the figure, the surface potential of the developing roller 3 including the toner layer may change in a time longer than the time required for one rotation of the JJ2 image roller 3. In this case, the difference between the surface potential of the developing roller 3 outputted from the first difference circuit 9 and the voltage value of the developing bias, that is, the difference potential, is sent to the second difference circuit 12 through the delay circuit 11, and In step 11112, the differential potential that is the output of the first differential step Hr9 is subtracted from the output value from the reference bias power source 3, and this is applied to the toner supply roller 5 as a final bias. As a result, the toner replenishment bias is appropriately corrected so that the surface potential in the developing area of the developing roller 3 is maintained constant.

In addition, the surface potential of the developing roller 3 including the toner layer is determined based on the potential change due to the uneven thickness of the surface layer of the developing roller 3 or the uneven thickness of the thin toner layer, as shown in FIG. When changing according to the rotation period, the measured value of the surface potential of the developing roller 3 within a predetermined rotation time set to at least one revolution of the developing roller 3 is sampled, and the surface potential including the sampled toner layer is sampled. The measured value of the surface potential of the developing roller 3 is smoothed by an integrating circuit provided in the arithmetic circuit 8. -Then, this smoothed value is outputted to the first difference circuit 9 as the surface potential measurement value of the developing roller 3. As a result, as described above, the toner replenishment bias voltage is appropriately corrected so that the surface potential in the development area of the development roller 3 is maintained constant.

Furthermore, as shown in FIG. 5, the measured potential includes minute potential unevenness or minute potential fluctuation in the surface potential of the developing roller 3 based on the unevenness of the toner thin layer due to the toner particle size distribution mentioned above or noise. Sometimes. In this case, the developing roller 3 within a predetermined minute time
The surface potential measurements of the developing roller 3 including the sampled toner thin layer are smoothed by an integrating circuit provided in the arithmetic circuit 8. Then, this smoothed value is outputted to the first difference circuit 9 as a surface potential measurement value of the developing roller 3, so that the toner replenishment bias voltage can be appropriately corrected in the same way as described above. There is.

As described above, in this embodiment, even if minute potential fluctuations are included in the measured potential, they are smoothed and compared, so that unnecessary fluctuations in the applied bias voltage are suppressed, and the toner The replenishment bias voltage control operation is performed smoothly. Furthermore, Figure 3,
When the potential fluctuations shown in FIG. 4 and FIG. 5 are combined, the above-mentioned control operations are executed in combination, and as a result, appropriate development characteristics can be obtained at all times. ing.

Furthermore, the developing roller 23 in the apparatus example shown in FIG. 6, in which the same components as those in the apparatus example shown in FIG.
A medium-resistance elastic layer 23b is attached around the support 23a formed from a conductive metal core, and a surface coating layer 23c is further applied on the medium-resistance elastic layer 23b. There is. Then, the surface potential of the developing roller 23 is measured after the developing operation is performed.
Two surface electrometers 7 and 27 are provided. The probes 7a and 27a of these two surface electrometers 7 and 27 are arranged close to the surface of the developing roller 23 at a predetermined distance from each other. The distance between the probe 27a on the upstream side provided immediately after the development area and the probe 7a provided on the downstream side is the same as that of the development roller 2.
The distance between the probe 27a on the upstream side and the center of the developing area is set to a distance that requires t at the moving speed of the developing roller 23.

To specifically explain an embodiment of the developing method of the present invention using such an example of an apparatus, first, the attenuation rate is measured from the two surface electrometers 7 and 27 with respect to the developing roller 23 having a medium resistance type time constant. is determined, and bias control is performed while taking into account the distance between the development area and the measurement point. As a result, the control operation is performed smoothly as in the above embodiment.

Next, in the apparatus example shown in FIG. 8, in which the same components as the apparatus example shown in FIG.
The probe 7a of the surface electrometer 7 in the embodiment shown in the figure is arranged in the upstream region of the development area in the rotational direction of the development roller 3, and the surface electrometer 7
The probe 7a is arranged in the downstream region of the toner layer regulating blade 6. In this example device, the surface potential of the developing roller 3 is measured after the thin layer of toner is formed. Furthermore, in the apparatus example shown in FIG. 9, the surface electrometer 7 in the embodiment shown in FIG.
, 17 are arranged in an upstream region of the 1 fl image area and downstream of the toner layer regulating blade 6 in the rotating direction of the developing roller 3. In this example of the apparatus as well, the surface potential of the developing roller 23 is measured after the thin layer of toner is formed.

Even when using the device example shown in FIG. 8 or FIG. 9, respectively, the control operation of the bias voltage for toner replenishment is performed smoothly and the developing roller 3, The surface potential in the development area 23 is maintained constant.

Furthermore, the example of the apparatus shown in FIG. 10 has approximately the same configuration as the example of apparatus shown in FIG. In addition, a urethane layer with a thickness of 0.5 ms is adopted as the dielectric layer 33c, and reversal development (N/P curse image) using negative and positively charged toner is performed. It is now possible to do so.

Further, the developing roller 3 before the developing operation is placed in the upstream region of the developing area in the rotational direction of the developing roller 33 and in the downstream region of the toner layer regulating blade 6.
A probe 7a of a surface electrometer 7 is provided to measure the surface potential of the surface electrode 3. Probe 7 of this surface electrometer 7
a is arranged close to the surface of the developing roller 33, and the detection output Vs□ from the surface electrometer 7 is sent to the first difference circuit 9 via the arithmetic circuit 8. 1st above
The voltage value V of the developing bias applied to the developing roller 33 from the power supply circuit 34 is inputted to the difference circuit 9, and the voltage value V of the developing bias applied to the developing roller 33 is compared with the detected surface potential measurement value of the developing roller 33. The deviation from the voltage value of the developing bias, that is, the differential potential V Oe F is calculated and output by the first difference circuit 9. The voltage value vll of the developing bias is initially set to -500V.

Further, the arithmetic circuit 8 is provided with an integral circuit, and the surface potential measurement value of the developing roller 33 measured during a certain period of time is sampled and smoothed by this integral circuit. This smoothed value is output to the first difference circuit 9 as a surface potential measurement value of the developing roller 33.

Furthermore, the deviation signal output from the first difference circuit 9 is transmitted to a delay circuit 11 formed from a delay element such as a COD.
is applied to. This delay circuit 11 has the function of delaying the output from the first difference circuit 9 by the travel time t from the potential measurement position to the toner regulation area and sending it to the second difference circuit 12. In the second difference circuit 12, the deviation difference potential VD-, which is the output of the first difference circuit 9, is subtracted from the output value V+ttp from the reference bias power supply 13, and this is the final toner regulation bias voltage V.
The CNT is applied to the toner layer regulating blade 6. In other words, what is the relationship between these potentials?

It will be expressed as VCNT=(vo, -(vs□-■6)). Here, the output value V from the reference bias power supply 13. , are set to -500V.

Note that for the toner replenishment roller 5, in addition to the output VB from the power supply circuit 34, the output VSF from the power supply circuit 35 is also applied.
A bias voltage for toner replenishment equal to the sum of the above is applied.

In a developing method using such an example device, if the surface potential v,1 of the developing roller 33 is on the positive side of the developing bias voltage v6, the toner regulating bias voltage V C
NT is controlled to be more negative than when measuring the surface potential vs. of the developing roller 33, and a voltage is applied.

For example, when the surface potential Vsx of the developing roller 33 is equal to the developing bias voltage VII (vs□=■.), the output value vFl from the reference bias power supply 13! F
(-500V) is directly output to the toner layer regulating blade 6, and when the surface potential (6) of the developing roller 33 is (developing bias voltage V, -100V), (the output value VR1 from the reference bias power supply 13, + 100V)
is output to the toner layer regulating blade 6, so that the so-called development potential is maintained constant. Such control/adjustment operations are performed between transfer sheets or at the time of rising.

In the above equation, the gain (A, A) in each differential circuit is
Although 8) is omitted, it can be applied to any state as long as it is determined based on the initial setting conditions. Furthermore, although each of the above-mentioned embodiments uses a negative polarity toner based on a reversal development method, the present invention can be similarly applied to a normal reversal development method.

Next, as shown in FIG. 12, the developing roller 43 in the device example shown in FIG. An elastic layer 43b of medium resistance is attached around a support body 43a formed of a conductive metal core, and
Further, a surface coating layer 43c is deposited on the medium resistance elastic layer 43b. Two surface electrometers 7 and 27 are provided to measure the surface potential of the developing roller 43 before a developing operation is performed. The probes 7a and 27a of these two surface electrometers 7 and 27 are spaced apart from each other by a predetermined distance from the developing roller 43.
is placed close to the surface of the The distance between the probe 7a on the downstream side provided immediately before the development area and the probe 27a provided on the upstream side thereof is set to a distance that requires tl at the moving speed of the development roller 23, and The distance between the probe 7a and the center of the developing area is set to a distance that requires t2 at the moving speed of the developing roller 43.

In the developing method of the present invention using such an example of an apparatus, first, the attenuation rate is determined from the two surface electrometers 7 and 27 for the developing roller 43 having a medium resistance type time constant. Bias control is performed while taking into account the area and the distance to the measurement point. As a result, the control operation is performed smoothly as in the above embodiment.

Furthermore, in the device examples shown in FIGS. 13 and 14, a roller-shaped toner layer regulating blade 6 is used as the toner regulating member in the device examples shown in FIGS. Toner layer regulating roller 56
are used respectively. In this embodiment as well, the control operation of the toner regulating bias voltage is carried out smoothly in the same way as in the above-mentioned embodiments.

Note that the surface electrometer 7 in each device example shown in FIGS. 10 to 14. The F probes 7a and 17a can also be placed in the downstream region of the development region.

[Effects of the Invention] As described above, the present invention is capable of maintaining the development potential constant before and after the development process even if the surface potential of the toner carrier includes potential fluctuations. The detection value of the surface potential of the toner carrier measured within a predetermined period of time is sampled, and the toner replenishment bias voltage value or toner regulation bias voltage value to be newly applied is determined and controlled based on the measured surface potential value. Because I decided to do this,
Even when a dielectric layer, resistor layer, or insulating layer is provided on the toner carrier, the so-called development potential can be maintained constant, and good development characteristics can be maintained without fluctuations in development characteristics. can be done.

[Brief explanation of the drawing]

FIG. 1 is an explanatory longitudinal cross-sectional view showing an example of a developing device for carrying out the present invention, and FIG. 2 is a partially enlarged longitudinal cross-sectional view showing the structure of a toner carrier provided in the developing device in FIG. 3, 4, and 5 are diagrams showing variations in the surface potential of the toner carrier, and FIG. 6 shows another example of a developing device for carrying out the present invention. FIG. 7 is a partially enlarged vertical cross-sectional view showing the structure of the toner carrier provided in the developing device in FIG.
9, 10, 11, and 13. FIG. 14 is a longitudinal cross-sectional explanatory view showing another example of a developing device for carrying out the present invention, and FIG. 2 is a portion showing the structure of a toner carrier provided in the developing device in FIG. 11. It is an enlarged longitudinal section explanatory view. DESCRIPTION OF SYMBOLS 1... Developing device, 3, 23, 33, 43... Developing roller, 4... Photosensitive drum, 6, 56... Toner layer regulating member, 7, 27... Surface electrometer, 7a , 27a
...Probe, 8... Arithmetic circuit, 9, 12... Differential circuit, 11... Delay circuit. (Other names) Bath 4 flash)'P) 2 mouths,'? ■ Aσ phantom form 4 phantom development v) v ■ Su question 6 form 60 % Zoro AIO Kunihisa 740 form 42 days 3 form 4σ mouth form 140

Claims (1)

[Claims] 1. Supplying toner from a toner supply member to a toner carrier under a predetermined bias voltage, and carrying the toner carrier cyclically while holding the toner on the surface of the toner carrier, and developing. In the developing method, the surface potential of the toner carrier in the development region is measured, and a voltage is applied to the toner replenishing member so that the surface potential of the toner carrier is maintained constant. A developing method characterized in that the bias voltage applied is adjusted and controlled. 2. The toner held on the surface of the toner carrier is made into a thin layer by a toner regulating member under a predetermined bias voltage, and the toner carrier is cycled while maintaining the thin toner layer on the surface of the toner carrier. In a developing method in which the toner carrying member is conveyed and a developing step is executed in a developing area, the surface potential of the toner carrying member in the developing area is measured, and the toner is transported so that the surface potential of the toner carrying member is maintained constant. A development control method characterized by adjusting and controlling a bias voltage applied to a regulating member.