CN1280682C - Image forming apparatus - Google Patents

Abstract

An image forming apparatus of non-contact developing method using two-component developer material which is capable of obtaining a clear image free from fogging, ghost and toner contamination. The image forming apparatus has at least one developing unit which develops an electrostatic latent image on a photosensitive body with a toner thin layer formed on the surface of a developing roll wherein a toner thin layer forming region on the developing roll is smaller than a magnetic brush forming region on the magnetic brush.

Description

Image processing system

Technical field

Duplicating machine, printer, facsimile recorder or their image processing systems such as compounding machine of electrofax mode have been the present invention relates to utilize, particularly relate to use and make the charged two-component developer of nonmagnetic toner by magnetic carrier, on developing roller, only keep charged toner, its electrostatic latent image that circles in the air is carried on a shoulder pole on the latent image of holding on the body (photoreceptor), use makes the mixing visualization way of this developable latent image, the change of the image color when suppressing development hysteresis and continuous lettering, the just image processing system of the image that the energy long term maintenance is stable.

Background technology

In the past, as non-contacting 1 composition development means, make the charged two-component developer of nonmagnetic toner to using by magnetic carrier, on developing roller, only keep charged toner, making it fly to electrostatic latent image carries on a shoulder pole on the electrostatic latent image of holding on the body (photoreceptor), thereby the noncontact visualization way of developable latent image is studied, but, in recent years, as the visualization way that can form image at a high speed, particularly also study holding the 1 magnetic drum colour superimposition mode that forms a plurality of coloured images on the body (photoreceptor) successively in the electrostatic latent image load.In this mode, by holding correctly overlapping toner on the body (photoreceptor), just can form the few coloured image of color displacement, thereby be attracted attention by common people as the technology of the colored high image qualityization of correspondence in electrostatic latent image load.

In addition, because high speed in recent years so use the multiple photoreceptor that corresponds respectively to multiple color, forms coloured image synchronously with sending to of recording member, on recording member, carry out the series system of colour superimposition and paid close attention to by people.In this mode, though aspect high speed, have superiority, because must handle the member alignment arrangements to electronic photo of all kinds, so the shortcoming of maximization is arranged.As its countermeasure, the someone has proposed to make photoreceptor interval each other to narrow down, and disposes the small-sized tandem type image processing system of the image forming part of miniaturization.

And, in the small-sized tandem type image processing system that constitutes like this,, be favourable so adopt vertical developing parts because make the size of Width of image forming part minimum.Promptly on layout, be preferably on the upper direction of photoreceptor and dispose developing parts.But, binary visualization way in the past exists the unavoidable problem of the following stated: promptly when like this developing parts being configured to when vertical, the backflow of developer, promptly become complicated from the developer mixing part to supply near the developing member of photoreceptor, occur the limit on equipment miniaturization, simultaneously carrier is to the adhering to of photoreceptor, descended and the toner that causes disperses etc. by the carried charge of toner.

As other method, also proposed not use 1 composition visualization way of carrier, but existed the following stated problem: in the mode that makes developing roller contact photoreceptor, can cause the moment of torsion change of photoreceptor, the weakness of encouraging tandem type is a color displacement.In addition, because with the non-contacting mode of photoreceptor under, make toner charged with the charging cylinder, with the bed thickness on the elastic limit scraper plate restriction developing roller, so the adjuvant of toner makes charged ability drop attached on the charging cylinder, perhaps toner is attached on the limiting scraper, make the formation of layer become inhomogeneous, thereby cause image deflects.

As one of means that address these problems, proposed in the tandem type image processing system, also use described such two-component developer to make toner charged, then the mixed type visualization way that by noncontact toner is dispersed for photoreceptor.As such prior art, at United States Patent (USP) the 3rd, 866, the following stated scheme is disclosed in No. 574 communiques: promptly hold body (photoreceptor) for the electrostatic latent image load, the toner cylinder (developing roller) that is provided with in noncontact upward forms thin layer with nonmagnetic toner, makes this toner fly to electrostatic latent image by AC field and carries on a shoulder pole on the latent image of holding on the body (photoreceptor).In addition, at United States Patent (USP) the 3rd, 929, the following stated scheme being disclosed in No. 098 communique: promptly uses magnet drum, developer is advanced on the toner cylinder, toner is transferred on this toner cylinder, form the mixed type developing parts of toner layer.

And, aspect theoretical, on electrofax association magazine the 19th volume No. second (1981), published report, opened the application that has in the clear 59-121077 communique as special permission the spy about the formation of the toner layer on the developing roller that has used two-component developer from Toshiba (Co., Ltd.).

But in these motions, though use the two-component developer can be to toner drum-shape straticulation, when toner charged high, it is difficult that the separation of the toner on the toner cylinder becomes, and strong AC field must be arranged.Because this electric field society electrostatic latent image load is held the toner layer confusion on the body (photoreceptor), so produced problem in colour superimposition.Therefore, open in the flat 3-113474 communique the spy, proposed to hold the auxiliary electrode that is made of tinsel has been set between the body (photoreceptor), on this auxiliary electrode, added weak AC field, the so-called powder cloud development method that the toner of development is not disarrayed in toner cylinder and electrostatic latent image load.

In addition, in the described prior art, the charged control of toner is complicated, surface potential of increasing outside being necessary on photoreceptor and big development electric field.Therefore, if on developing roller, produced the consumption zone and the on-consumable zone of toner, the attachment state of the toner on this cylinder and the potential difference (PD) of toner will produce skew, so, as shown in Figure 4, the so-called hysteresis phenomenon that the part of the developed image of front is developed as afterimage (afterimage) when the development of following takes place easily.Promptly in Fig. 4,13 stereo-pictures that constitute by the black surround of rectangle, the 16th, then its half tone image than this stereographic map image width, when on developing roller, having produced consumption zone and on-consumable zone, if then this stereo-picture is printed this half tone image 16, then produce the such afterimage (afterimage) of 14A among Fig. 4 (b).

In order to prevent it, open the development that has proposed in the flat 11-231652 communique to be used to remove on the developing roller the spy and remain the member of toner and the retracting device of the toner that removes.In addition, as the method that reclaims the toner on the shadow cylinder exactly, open the scheme that has proposed to use special-purpose recovery cylinder in the 2000-81788 communique the spy.Open flat 7-72733 communique, spy the spy and open and proposed in the flat 7-92804 communique to utilize between copy and the copy or between paper, the toner on the shadow cylinder is recovered on the magnet drum, make the charged stable method of toner with potential difference (PD); As having used the corresponding method of the elimination hysteresis phenomenon of magnetic brush, open the half range value zone that has proposed the magnetic flux density by making magnet drum in the flat 7-128983 communique the spy and broaden, seek to reclaim the method for the recovery and the supply of the toner on the shadow cylinder.

In addition, as the control method of the developing parts of tandem type, the action of opening the developing parts that has proposed to make the image forming part beyond the image forming part that carries out reproduction process in the clear 63-249164 communique the spy stops, and prevents the application of the deterioration of developer.In addition, proposed the following stated technical scheme in Te Kaiping-No. 667546 communique: promptly switch the high pressure be added between developing roller and the magnet drum with high frequency, alternately forming from magnet drum provides the electric field of toner and peels off the technology of the electric field of toner from developing roller to magnet drum to developing roller; Except magnet drum, also be provided with the toner peeling member in addition in addition, the electric toner of peeling off, reclaiming on the developing roller is recovered on the magnet drum the toner of peeling off, reclaiming is electric then.

But, open the tinsel that the powder cloud development method put down in writing in the flat 3-113474 communique is very easy to pollute auxiliary electrode described spy, and, because produced based on the image degradation of vibration etc., so can not become a kind of general method.And, opening flat 11-231652 communique, spy the spy opens flat 7-72733 communique, spy and opens flat 7-92804 communique, spy and open flat 7-128983 communique, spy and open clear-No. 121077 communiques, spies and open the device of describing in the 2000-81788 communique etc. and also be necessary to be provided with the removal device of toner and reclaim cylinder, owing to reclaim adding of bias voltage etc. especially, the stress of toner increases, the main cause that becomes the endurance quality of toner and change, or form at the layer of the development followed developing roller regularly and to need the time, thereby influenced high speed.In addition, when long-term the use, because the endurance quality of carrier worsens, the charging property of toner changes, big variation takes place in the charged characteristic of the toner on the developing roller, the charged distribution of the toner of supply and the toner of recovery broadens, and becomes dispersing and fuzzy reason based on charged bad toner.And changing the carrier that worsens also is trouble, so in fact be difficult to practical.

In addition, opening the device of representing in clear 63-249164 communique and the flat 6-67546 communique of Te Kai the spy need make the action of the image forming part developing parts in addition that carries out reproduction process stop, or switch device and the control be added to the high pressure between developing roller and the magnet drum with high frequency, so, not only must pay high price, and its structure is: developing parts and toner cylinder, magnet drum and agitating member and row arrangement, thus cause being difficult to miniaturization.

And, in these prior aries, when the toner thin layer that uses in the development that on developing roller, is formed on the latent image on the photoreceptor, after developing roller turns around, when entering the development of second circle, the toning dosage of the toner layer on the developing roller is different sometimes, in addition, after the development of having carried out high concentration, after second circle, the absolute magnitude deficiency of toner also can take place, and causes the phenomenon of the density loss of image.In order to eliminate such phenomenon, considered developing regularly, made developing roller idle running, guaranteed sufficient toning dosage, or the method for fully guaranteeing to develop at interval etc., but,, just increased for the load of developer if improve the rotation number of developing roller for photoreceptor, thereby the charged deterioration that causes toner, if fully guarantee in addition to develop at interval, then print speed printing speed descends, thereby can't deal with problems.

And these prior aries take place easily as the afterimage (afterimage) shown in described Fig. 4 (b) and the image that develops is so-called hysteresis phenomenon, how to address this problem just to have become a problem.

These prior aries add potential difference (PD) opposite when forming image between developing roller and magnet drum when non-image formation, the remaining toner on the developing roller is recovered to magnet drum one side, have prevented the generation of this hysteresis phenomenon.

That is, for the remaining toner on the developing roller being recovered to magnet drum one side, the externally-applied potential difference is effectively between two cylinders, if improve potential difference (PD), it also is true easily that the recovery of remaining toner becomes.

But, for handle is recovered on the magnet drum at the toner layer of comparing several times of thickness on the developing roller with the particle diameter of toner, be necessary to make the developing roller rotation, make on the carrier of this remaining toner attached to the magnetic brush of magnet drum formation, reclaim, its result, by the rotation of two cylinders, reclaim remaining toner.

If like this, if make the peripheral speed of magnet drum also faster than the peripheral speed of developing roller, except increasing the chance that magnetic brush contacts with developing roller, and the remaining toner on the developing roller worked, shear stress based on magnetic brush has improved, and just can weaken remaining toner on the developing roller to the contact pressure of developing roller.

As a result, though not between developing roller and magnet drum externally-applied potential poor, under equipotential, because high magnetic carrier, just can reclaim remaining toner effectively.The inventor is conceived to this fact.

But, shown in Figure 17 (b), the width H1 that the formation width H1 of the toner layer of the short transverse of developing roller 32 and the magnetic brush of magnet drum 31 form the short transverse in zone is same length, be configured in the same position of developer container 12a, 12b, if on the recording chart shown in (a) 17, form image, two afterimages that edge 14B, 14C are such of recording chart 17 have then been formed.

Shown in Figure 16 (a), when with identical size, identical level configurations developing roller 2 and magnet drum 1, by carrier 24A ₁Reclaimed development remaining toner 15a, by carrier 24A ₂Reclaimed toner 15b, by carrier 24A ₃ Reclaimed toner 15c, shown in Figure 16 (b), when developing roller 2 is higher than magnet drum 1, reclaimed toner 15c by carrier 24B, and toner 15a and toner 15b do not form the magnetic brush based on carrier in the position higher than carrier 24B, so be not recovered.

Therefore, as shown in figure 15, the formation by making magnet drum 1 the sleeve axial width H3 of magnetic brush bigger than the axial width H1 of the toner layer that has formed developing roller, development remaining toner 15a, 15b, 15c are by the carrier 24C of magnetic brush ₂, 24C ₃, 24C ₄Reclaim.

But when image formed, because the potential difference (PD) that forms between developing roller 2 and magnet drum 1, toner 15d, 15e, the 15f of the carrier 24C1 of magnetic brush flew on side, the side 2a of described developing roller 2, and is captured.Though when non-image formation, development remaining toner 15a, 15b, 15c are reclaimed by magnetic brush, toner 15d, 15e, 15f do not contact magnetic brush, thus be not recovered, and residual dispersing, thereby in the pollution machine.

But, described spy opens flat 11-231652 communique, the spy opens in the device of describing in the flat 7-128983 communique, because the removal device of toner and the special recovery bias voltage that adds, the stress of toner has increased, and becomes the endurance quality of toner and the main cause changed.In addition, when long-term the use, because the endurance quality of carrier worsens, the charging property of toner changes, big variation takes place in the charged characteristic of the toner on the developing roller, the charged distribution of the toner of supply and the toner of recovery broadens, and becomes dispersing and fuzzy reason based on charged bad toner.And changing the carrier that worsens also is trouble, so in fact be difficult to practical.

In addition, Te Kaiping 6-67546 communique, spy open flat 7-72733 communique, spy, and to open the hybrid type developing apparatus of describing in the flat 7-792804 communique be to hold the powder cloud development method that is provided with electrode between the body (photoreceptor) at toner cylinder and electrostatic latent image load, be very easy to the pollution metal silk, and, might vibrate the image deterioration that causes.Open flat 7-72733 communique the spy, the spy opens in the flat 7-92804 communique and describes in the developing parts, because the toner layer on the developing roller adds certain voltage from magnetic brush and forms, so be subjected to electric field and friction from magnetic brush when continuous printing etc. repeatedly, the toner carried charge on the developing roller is than the toner height of (in the two-component developer) in the magnetic brush.And, in this developing parts, use potential difference (PD) to carry out the recovery of the toner on the developing roller, but, because the toner on the developing roller almost hardly with magnetic brush in toner replace, removed by magnetic brush, so can reclaim toner at short notice, but, because toner on the different developing roller of carried charge and the toner moment in the magnetic brush are mixed, so the charged distribution of the toner in the two-component developer broadens, produced and had the charged etc. of reverse charge, thereby caused from problems such as the dispersing of the toner of magnetic brush, image deflects.

And, opening 2000-250294 communique, spy the spy, to open the device of describing in the 2000-250295 communique be that electrode with the surface that embeds toner cylinder (developing roller) produces the toner cloud, thereby mix such developing parts that develops, its structure is provided with the brush that is used for applying bias on electrode for make toner fly to position on the toner cylinder etc. two at developing location and from magnet drum, because complex structure, only this just makes cost very high.

Summary of the invention

The existence of problem in view of the above, the objective of the invention is to: a kind of image processing system that uses the noncontact visualization way of two-component developer is provided, particularly can avoid the generation of bluring, and the generation of inhibition afterimage (afterimage), thereby the image processing system of the image of formation distinctness.

In addition, other purposes of the present invention also are: a kind of image processing system that can prevent to adhere on the side of developing roller from the toner of magnet drum is provided.

And, the present invention is in the developing method that the small-sized mixed type developing parts that can constitute the small-sized series connection image processing system that is suitable for obtaining for a long time stable image quality is provided, also provide to contain and do not make the developing parts complexity, make the toner layer on the developing roller always certain, the generation of the afterimage when preventing to develop continuously, for developing roller provides charged exactly toner, can not cause the dosage difference of mixing colours, or image color descends, and can keep the image processing system of the mixed type developing parts of stable image quality for a long time.In view of the above, just can be with the small-sized series connection image processing system of low price composing images stay in grade.

And, the present invention also aims to: provide not make the developing parts complexity, the generation of the afterimage when preventing to develop continuously, for developing roller provides charged exactly toner, just can obtain the image processing system of stable image quality for a long time, particularly can constitute the tandem type image processing system of small-sized processing element.

In addition, other purposes of the present invention also are: when the extremely low image of continuous printing lettering rate or when only printing specific color, sometimes the charged rising of developer, the development amount of toner changes, but in the present invention, being provided at causes before the image change, discharges the deterioration toner from processing element, and the tandem type image that can obtain stable coloured image forms device.

And other purposes of the present invention also are: be provided at and have in the image processing system of the supply parts of the described developer of developing parts supply and the described supply parts of control, prevent the decline of image color and fuzzy, and the invention of not wasting toner.

In order to reach above-described purpose, the present invention 1 image processing system comprise at least more than one, the insulation by magnet drum or high-resistance toner and based on the magnetic brush of carrier, utilization is formed on the outer lip-deep toner thin layer of developing roller that is added with the development bias voltage, the developing parts that electrostatic latent image on the photoreceptor is developed is characterized in that:

Make be formed on the lip-deep axial toner thin layer of described developing roller form the zone than the axial magnetic brush that is formed on described magnet drum one side form the zone little.

According to related invention, to form the zone little because the axial toner thin layer that forms on the surface of described developing roller forms axial magnetic brush that the zone forms than described magnet drum one side, so can form the toner thin layer zone that fully covers the electrostatic latent image zone that forms on the photoreceptor on the developing roller surface of correspondence.

On the other hand, when forming axial toner thin layer that the zone forms on than developing roller surface, axial magnetic brush that magnet drum one side forms forms zone hour, at the two ends of developing roller, when image forms, can't form the toner thin layer that magnetic brush is evenly distributed.

In addition, when non-image formation, the magnetic brush of the magnet drum toner thin layer zone on the developing roller corresponding that do not rub with the whole electrostatic latent images zone that forms on the photoreceptor, therefore, not in the part that is rubbed by magnetic brush, residue toner on the developing roller is not recovered and is remaining, when image forms, causes the generation of afterimage.

Form regional little because relevant invention makes the axial toner thin layer that forms on the surface of developing roller form the regional axial magnetic brush that forms than described magnet drum one side, so can fully have been covered the toner thin layer zone in the electrostatic latent image zone that forms on the photoreceptor in developing roller one side, when image forms, can not produce the deficiency of toner supply in the Width outside in the electrostatic latent image zone that on photoreceptor, forms, thereby can carry out image fully forms, and the recovery of the residue toner on can developing roller is insufficient, also can not produce afterimage.

And the present invention 2 image processing system is in the present invention 1 image processing system, is preferably in the non-toner thin layer that two ends that described toner thin layer forms the zone are formed with insulation or the high resistance area higher than the resistance of toner and forms the zone.

According to correlation technique, form the zone because be preferably formed as the non-toner thin layer of insulation or the high resistance area higher at the two ends that described toner thin layer forms the zone than the resistance of toner, so can adhering toner at these two ends, just can prevent that this adhering toner is not recovered and in the pollution machine, prevent attached on the photoreceptor and influence image and form, thereby can form preferable image.

In addition, when image forms, because the potential difference (PD) that forms between described developing roller and the magnet drum, on described developing roller, formed toner thin layer, when non-image formation, toner on the described developing roller is under 0 the state in described potential difference (PD), and the magnetic brush with described magnet drum of the peripheral speed faster than described developing roller reclaims.

According to correlation technique, when non-image formation, remaining toner on the described developing roller is under 0 the state in the potential difference (PD) that forms between described developing roller and the magnet drum, is reclaimed by the magnetic brush of the described magnet drum with peripheral speed faster than the peripheral speed of developing roller.

Faster by the peripheral speed that makes magnet drum than the peripheral speed of developing roller, except increasing the chance that magnetic brush contacts with developing roller, and improved based on the shear stress of magnetic brush, remaining toner on the developing roller is worked, just can weaken remaining toner on the developing roller to the contact pressure of developing roller, though not between developing roller and magnet drum externally-applied potential poor, under equipotential, because high magnetic carrier just can reclaim remaining toner effectively.

In addition, 150～400 μ m that are set between described photoreceptor and the developing roller, and when image forms, also be effective means of the present invention at the toner thin layer that described developing roller forms 5～10 times of thickness of toner mean grain size from described magnet drum.

According to correlation technique, 150～400 μ m that are set between described photoreceptor and the developing roller, if should be narrower than 150 μ m at interval, just be easy to generate fuzzy, if wideer, just be difficult to toner is flown on the photoreceptor, thereby can't obtain sufficient image color than 400 μ m.

In addition, the thickness of the toner thin layer on the developing roller when forming image is set to 5～10 times of mean grain size of toner, if the mean grain size of toner is 7 μ m, then this thickness is 35～70 μ m, if the thickness of toner thin layer surpasses 70 μ m, then being difficult to provides toner to photoreceptor, when developing, produce concentration difference, in addition, when reclaiming toner, can't reclaim all development remaining toners, thereby produce the afterimage phenomenon.

In addition, the mean grain size of carrier preferably is set to 3～9 times of toner mean grain size.If the mean grain size of carrier less than 3 times of the toner mean grain size, then attracts the power of toner little, be difficult to reclaim, if greater than 9 times of the external diameter of toner, just reduced the chance that contacts with toner, therefore, the time of reclaiming toner is elongated.

In addition, the development bias voltage between preferably described magnet drum and the developing roller is set to 100V～250V, forms the toner thin layer of 5～10 times of thickness of toner mean grain size on the described developing roller.

According to correlation technique, just can when forming, image on developing roller, form the toner thin layer of 5～10 times of thickness that are equivalent to the toner mean grain size.Therefore, just can form the image that does not have afterimage and blur with appropriate image color, and, with regard to the toner thin layer of the recovery that can form the remaining toner that is suitable for developing.

And, the 1 described image processing system according to the present invention, the development bias voltage that described development bias voltage is an overlapping AC bias on first Dc bias, the bias voltage that adds on the described magnet drum is second Dc bias, it is characterized in that:

When being formed for the toner thin layer of the developable latent image on the photoreceptor on described developing roller, the potential difference (PD) the when toner thin layer that the potential difference (PD) between described first and second Dc biases when first lap is formed toner thin layer is provided with later on than second circle forms is big.

Like this, when forming the toner thin layer that uses in the development of the latent image on the photoreceptor on developing roller, the potential difference (PD) the when toner thin layer at first lap is formed between described first and second Dc biases is provided with greatlyyer than the potential difference (PD) when the later toner thin layer of second circle forms.In view of the above, just can prevent when the potential difference (PD) between first and second Dc biases in the past is all same after the first lap and second circle, produce enter the development of second circle time, the different phenomenon of the toning dosage of toner layer and first lap on developing roller, and after having carried out the development of high concentration, the absolute magnitude deficiency of toner causes the decline of image color after second circle.Not only when developing, begin just to have guaranteed the toner layer of necessary amount from the first lap of developing roller, and, even after the development of having carried out high concentration, the absolute magnitude deficiency of toner also can not appear, can not cause the decline of image color.

Therefore, the generation of the afterimage in the time of preventing to develop continuously is provided, for developing roller provides charged exactly toner, can not cause the dosage difference of mixing colours, or image color descends, can keep the control method of the mixed type developing parts of stable image quality for a long time, in view of the above, just can be with the small-sized series connection image processing system of low price composing images stay in grade.

And, be provided with than the potential difference (PD) of big first lap after second circle as the present invention 2 is described, it is characterized in that:

Potential difference (PD) between first and second Dc biases of described first lap and the later potential difference (PD) of second circle are set at about 45～55V.

Promptly, when the potential difference (PD) of the first lap that is provided with later on greatlyyer than the second circle potential difference (PD) big 55V later than second circle is above, toning dosage on the developing roller increases, it is the reason that causes toner to disperse, in addition, when being discontented with 45V, just can not get significant effect, by be arranged on about about 50V (45～55V), just can prevent such phenomenon, when described development, begin just to have guaranteed the toner layer of necessary amount from the first lap of developing roller, and, even after the development of having carried out high concentration, the absolute magnitude deficiency that toner yet can not occur can not cause the decline of image color.

And, preferably it is characterized in that: before and after image forms and image forms and image next time form between or during the non-image formation between the recording medium when forming image continuously etc., make described developing roller and magnet drum keep rotation, potential difference (PD) between described first and second Dc biases produces the equipotential state, only add described AC bias, replace toner on the described developing roller with described magnetic brush and AC bias.

Like this, during non-image formation, make developing roller and magnet drum keep rotation, the state that generation equates the potential difference (PD) between first and second Dc biases, and, by only adding described AC bias, special devices such as removing scraper plate need not be set, or cause burden to toner, magnetic brush on the magnet drum contacts with toner layer on the developing roller, just can pass through the residual toner of brush effect recovery development based on the difference of each cylinder, and, just can carry out replacing based on the developer of the stirring of using stirrer.Therefore, just can easily reclaim the residual toner of development that causes afterimage, avoid the generation of bluring, suppress the generation of afterimage, thereby can form the image of distinctness.

In addition, the 1 described image processing system according to the present invention, the development bias voltage that described development bias voltage is an overlapping AC bias on first Dc bias, the bias voltage that adds on the described magnet drum is second Dc bias, it is characterized in that:

Before and after image forms, image forms and image next time form between, any one party or two sides during the non-image formation between the recording medium when forming image continuously etc., make described developing roller and magnet drum keep rotation, make described first and second Dc biases produce the equipotential state, and, only add described AC bias, replace toner on the described developing roller with described magnetic brush and AC bias.

Like this, during non-image formation, make developing roller and magnet drum keep rotation, the equipotential state that generation equates surface potential, by only adding described AC bias, only all do not reclaimed the toner on the developing roller by magnetic brush, and passing through AC bias, when having promoted the replacement of toner on the developing roller and toner in the magnetic brush, the carried charge distribution of toner when replacing is not almost changed, can not make developing parts complicate the generation of the afterimage in the time of just preventing to develop continuously, for developing roller provides charged exactly toner, obtain stable image quality for a long time.

And, in this AC bias, the AC bias that adds on described developing roller is a square wave, by making positive dutycycle when using the positively charged toner less than 45%, dutycycle negative when using electronegative toner is less than 45%, the replacement of the toner on the developing roller has been improved, solved problem such as disperse toner adhering on developing roller, dual imaging, toner, as mentioned above, developing parts is complicated, the generation of the afterimage in the time of just preventing to develop continuously is for developing roller provides charged exactly toner.

And, be between recording medium the time during the described non-image formation, make the length between this recording medium longer by control than the processing girth of described developing roller, even between recording medium, also can promote the toner on the described developing roller and the replacement of the toner in the magnetic brush, even when printing continuously, also can obtain stable image quality for a long time.

And, in order to promote the toner on the developing roller and the replacement of the toner in the magnetic brush, the rotational speed of described magnet drum is at least 1.0 times speed above the rotational speed of developing roller, and, make two cylinders to being rotated in the forward, use this velocity contrast, make magnetic brush contact developing roller, carry out the replacement of the toner on the developing roller, thereby can realize replacing the effect of toner exactly.

Tandem type image of the present invention forms device, the processing element that constitutes by the present invention's 1 described described developing parts and the photoreceptor magnetic drum corresponding that multiple number of colors is arranged with it, and the copying image of all kinds from this each processing element is formed image on recording medium or intermediate duplication body, it is characterized in that:

During the non-image formation of described each processing element or before beginning to form image, make described developing roller and magnet drum keep rotation, the equipotential state that generation equates the current potential between two cylinders under these potential states, reclaims remaining toner on the described developing roller with described magnetic brush.

Like this, by during non-image formation or before beginning to form image, make described developing roller and magnet drum keep rotation, the equipotential state that generation equates the current potential between two cylinders, the magnetic brush that forms on the magnet drum has all reclaimed the toner on the developing roller, having eliminated the development on the developing roller lags behind, suppress afterimage and fuzzy generation, so can provide charged exactly toner for developing roller, just can constitute and small-sized can obtain the processing element of stable image quality for a long time, in view of the above, just can constitute small-sized series connection image processing system.

And this moment, among the present invention, when in described each processing element, developing, when consumption of toner is lower than specified rate, can forcibly be discharged to toner on recording medium or the intermediate duplication body from processing element.

So, when consumption of toner is lower than specified rate, by forcibly toner being discharged to recording medium or the intermediate duplication body from processing element, when printing the extremely low image of lettering rate continuously or only printing specific color, just can prevent the charged rising of developer, the development amount of toner changes, toner deterioration before causing image change is discharged from processing element, just can obtain stable coloured image, just can constitute and small-sized can obtain the processing element of stable image quality for a long time, in view of the above, just can constitute small-sized series connection image processing system.

And, in the present invention, infer the consumption of described toner from the number of spots of view data of printing, when for this consumption of toner, the value representation of toner magnetoconductivity sensor is that certain value is when following, rise as the toner carried charge, forcibly toner is discharged on recording medium or the intermediate duplication body from processing element.

So, when the extremely low image of continuous printing lettering rate or when only printing specific color, charged (below be called Q/M) that just can prevent toner rises, electrostatic adhesion is on the surface of carrier 4 securely, magnetoconductivity output valve based on the developer of toner concentration (T/C) sensor descends, the developer toner use amount than reality that causes estimating is lacked, and not supply toner, thereby can constitute and small-sized can obtain the processing element of stable image quality for a long time, in view of the above, just can constitute small-sized series connection image processing system.

And these controls can be the toning dosage that is discharged to described recording medium or intermediate duplication body of measuring every kind of color by development amount detection part.

In addition,,, copy on the same part of the non-pass-through area on recording medium or the intermediate duplication body when being lower than the processing element of described given consumption of toner as a plurality of with the state of colour superimposition.

In addition, when the toning dosage that can often hold discharge, and when a plurality of processing units were discharged toner, the open country can be carried out this control at short notice.

And image processing system of the present invention comprises to the supply parts of the described developer of the present invention's 1 described developing parts supply and the control assembly of the described supply parts of control, it is characterized in that:

Described control assembly has: measure the image density of each paper used for recording according to described view data, this image density of accumulative total obtains the integrating block of accumulative total image density; According to described accumulative total image density, infer the supposition parts of the consumption of described developer; Forbidding in the time before described consumption reaches specified rate, forbid the parts of forbidding based on the supply of the described developer of described supply parts.

In above-described developer supply control device, the image density that accumulative total is obtained by view data, obtain the accumulative total image density, infer the consumption of developer according to the accumulative total image density, before this consumption reaches given amount, forbid the supply of developer, so in this forbids the time, old developer is used consumption, by filling developer after forbidding the time, new developer is provided for developer load immediately and holds near the body, just can prevent the decline of image color and blurs, and, just can use developer effectively.

And, according to image processing system of the present invention, comprise the supply parts of the described developer of the present invention's 1 described developing parts supply and the control assembly of the described supply parts of control, it is characterized in that:

Described control assembly has: measure the image density of each paper used for recording according to described view data, this image density of accumulative total obtains the integrating block of accumulative total image density; Forbidding in the time before described accumulative total image density reaches the value of predesignating, forbid the parts of forbidding based on the supply of the described developer of described supply parts.

In above-described developer supply control device, accumulative total obtains the accumulative total image density by the image density that view data obtains, before the accumulative total image density reaches the value of predesignating, forbid the supply of developer, so in this forbade the time, old developer was used consumption, if after forbidding the time filling developer, then new developer is provided for the developer load immediately and holds near the body, just can prevent the decline of image color and fuzzy, and, just can use developer effectively.

And described integrating block obtains described accumulative total image density for example according to described image density * printing number.

In addition,, comprise, it is characterized in that to the supply parts of the described developer of the present invention's 1 described developing parts supply and the control assembly of the described supply parts of control according to image processing system of the present invention:

Described control assembly has: the amount of the described developer in the described developing parts is detected as detecting developer level, if becoming, this detection developer level is lower than predetermined amount, control described supply parts, to the supply control assembly of the described developer of described developing parts supply; Measure the image density of each paper used for recording according to described view data, this image density of accumulative total, obtain the accumulative total image density, according to described accumulative total image density, infer the consumption of described developer, forbidding in the time before described consumption reaches specified rate, forbid the control assembly of forbidding based on the supply of the described developer of described supply parts.

In above-described developer supply control device, if becoming, the detection developer level is lower than predetermined amount, supply control assembly filling developer in developing parts just then, forbid the image density that control assembly accumulative total obtains from view data, obtain the accumulative total image density,, infer the consumption of developer according to the accumulative total image density, before this consumption reaches specified rate, forbid the supply of developer.Therefore, forbidding in the time that old developer is used consumption, after forbidding the time, by the control of supply control assembly, developer is arrived developing parts by supply, so new developer is provided for developer load immediately and holds near the body, just can prevent the decline of image color and blur.And, can not carry out vacation and develop, the use consumption of old developer has been prevented the waste of developer.

According to image processing system of the present invention, comprise to the supply parts of the described developer of the present invention's 1 described developing parts supply and the control assembly of the described supply parts of control, it is characterized in that:

Described control assembly has: the amount of the described developer in the described developing parts is detected as detecting developer level, if becoming, this detection developer level is lower than predetermined amount, control described supply parts, to the supply control assembly of the described developer of described developing parts supply; Measure the image density of each paper used for recording according to described view data, this image density of accumulative total, obtain the accumulative total image density, forbidding in the time before described accumulative total image density reaches the value of regulation, forbid the control assembly of forbidding based on the supply of the described developer of described supply parts.

In above-described developer supply control device, if becoming, the detection developer level is lower than predetermined amount, supply control assembly filling developer in developing parts just then, forbid the image density that control assembly accumulative total obtains from view data, obtain the accumulative total image density, before the accumulative total image density becomes set-point, forbid the supply of developer.Therefore, forbidding in the time that old developer is used consumption, after forbidding the time, by the control of supply control assembly, developer is arrived developing parts by supply, so new developer is provided for developer load immediately and holds near the body, just can prevent the decline of image color and blur.And, can not carry out vacation and develop, the use consumption of old developer has been prevented the waste of developer.

For example, if the described control assembly of forbidding is according to described image density * printing number, obtain described accumulative total image density, after the described image processing system starting, described supply control assembly work, if the printing number based on described image processing system reaches the number that sets in advance, describedly forbid control assembly work.And, also can be the starting of described image processing system after, described supply control assembly work if described image density becomes the density that sets in advance, is describedly forbidden control assembly work.

Like this, at first, make the work of supply control assembly, if the printing number reaches the number that sets in advance, or image density reaches the density that sets in advance, then make and forbid control assembly work, like this, forbidding in the time that the residual big developer (old developer etc.) of particle diameter is consumed near the developer load of developing parts is held body, its result, after forbidding the time, under the control of supply control assembly, developer is arrived developing parts by supply, new developer is provided for developer load immediately and holds near the body, just can prevent the decline of image color and blurs.And, can not carry out vacation and develop, the use consumption of old developer has been prevented the waste of developer.

And, describedly forbid that the time is to stipulate according to the stability bandwidth of the toning dosage that produces in the described developing parts, for example, stability bandwidth fixes in 5～50% the scope.And developing parts for example utilizes magnetic one composition visualization way to carry out the development of electrostatic latent image.

If carry out developer supply control according to the present invention, then produce fluctuation on the amount of the developer in developing parts.And the developer that the fluctuation in developing parts causes resupplies moves to the developer load in the short time and holds near the body.Its result, old developer is used consumption, and new developer is provided for developer load and holds body, thereby can prevent the decline of image color and fuzzy etc. effectively.The stability bandwidth of developer is preferably in for the developer in the developing parts in 5～50% the scope.If the stability bandwidth of developer is lower than 5%, then be difficult to avoid select to develop, and if the stability bandwidth of developer surpasses 50%, then the supply of developer forbids that the time is elongated, is difficult in the developer load and holds and form the developer thin layer on the body.

Description of drawings

Below, the brief description accompanying drawing.

Fig. 1 is used for illustrating that the tandem type image of embodiments of the invention forms the figure of the developing apparatus of the processing element of using in the device.

Fig. 2 is the figure of the basic layer structural model of electrostatic latent image load that expression is used among the present invention a-Si that holds body (photoreceptor).

Fig. 3 is the figure that is used to illustrate the suitable developing regional of the bias voltage on the developing apparatus that is added to image processing system of the present invention.

Fig. 4 is the figure that is used to illustrate owing to the generation that contains the afterimage that ratio produces of high resistance carrier and low resistance carrier.

Fig. 5 implements the embodiment that tandem type image of the present invention forms device.

Fig. 6 implements other embodiment that tandem type image of the present invention forms device.

Fig. 7 is the curve map of expression based on the change of the output valve of the magnetoconductivity sensor of the carried charge (Q/M) of toner.

Fig. 8 is that expression is when implementing according to the present invention to develop control and the different curve map of the carried charge (Q/M) of the toner when controlling of not implementing to develop.

Fig. 9 is the mode chart of the relation of explanation photoreceptor of example of the present invention and developing parts.

Figure 10 is the section plan of Fig. 9.

Figure 11 is the key diagram 1 of recovery state of the development remaining toner of explanation example of the present invention.

Figure 12 is the stereographic map of the developing parts of example of the present invention.

Figure 13 is the figure of the cross-section structure of the developing roller that uses in the invention of presentation graphs 9.

Figure 14 is the figure of other embodiment cross-section structures of the developing roller that uses in the invention of presentation graphs 9.

Figure 15 is the key diagram 2 of the recovery state of explanation development remaining toner.

Figure 16 is the key diagram 3 of the recovery state of explanation development remaining toner.

Figure 17 is the mode chart of the appearance of expression afterimage generation.

Figure 18 is for developing method of the present invention is described, and the curve map of the relation of the rotation number of the potential difference (PD) of expression magnet drum and developing roller and developing roller.

Figure 19 be expression developing method of the present invention with in the past developing method in based on the curve map of the formation situation of the toner layer of the rotation number of developing roller.

Figure 20 is the block diagram of expression based on an example of developer supply control circuit of the present invention.

Figure 21 is the process flow diagram that is used to illustrate the action of developer supply control device shown in Figure 20.

Figure 22 is the curve map that is used for illustrating the relation of the printing number of Figure 20 and image color.

Figure 23 is the curve map that is used for illustrating the relation of the printing number of Figure 20 and toner mean grain size.

Embodiment

With reference to the accompanying drawings, be illustrated with regard to example of the present invention.But, the size of the structural member of putting down in writing in this example, material, shape, relative position etc., unless specify, otherwise scope of invention is not limited thereto, only illustrative examples.

Fig. 1 is used for illustrating that tandem type image of the present invention forms the figure of the developing parts of the processing element that device uses, Fig. 2 is the figure of the basic layer structural model of electrostatic latent image load that expression is used among the present invention a-Si that holds body (photoreceptor), Fig. 3 is the figure of suitable developing regional that is used to illustrate the bias voltage of the developing parts that is added to image processing system of the present invention, Fig. 4 is the figure that is used to illustrate owing to the generation that contains the afterimage (afterimage) that ratio produces of high resistance carrier and low resistance carrier, Fig. 5, Fig. 6 is an embodiment who implements the tandem type image formation device of control method of the present invention, Fig. 5 is the structure example when electrostatic latent image load is held body (photoreceptor) and gone up the toner picture that forms and directly copy on the recording medium, Fig. 6 is after earlier the electrostatic latent image load being held body (photoreceptor) and gone up the toner that forms and look like to copy on the intermediate duplication body, the structure example when copying on the recording medium again.

In Fig. 1, the 1st, by magnet in internal configurations, generation is based on the magnet drum of the magnetic brush 10 of the carrier 4 that comprises in the developer, the 2nd, support, maintenance is based on the toner thin layer 6 of the toner 5 that is provided by magnetic brush 10, make the electrostatic latent image load hold the developing roller that the electrostatic latent image on the body 3 develops, the 4th, the carrier of toner, wherein, 4-1 is the low resistance carrier, 4-2 is the high resistance carrier, the 5th, and toner, the 6th, the toner thin layer on the developing roller 2, the 7th, hold the developing bias supply that adds the development bias voltage between body (photoreceptor) 3 and the developing roller 2 in the electrostatic latent image load, 7a is direct current (DC) bias voltage (V _Dc1) power supply, 7b exchanges (AC) grid bias power supply, the 8th, the direct current of magnet drum 1 (DC) bias voltage (V _Dc2) power supply, the 9th, the limiting scraper (shearing scraper plate) of the thickness of the magnetic brush 10 on the restriction magnet drum 1.

In Fig. 2, the 40th, electrostatic latent image load is held the matrix material of body (photoreceptor) 3, and the 41st, barrier layer, the 42nd, the photographic layer that constitutes by a-Si, the 43rd, sealer.And, in the following description when being expressed as a-Si electrostatic latent image load and holding " thickness " of body (photoreceptor) 3, be meant that the matrix material 40 of holding body (photoreceptor) 3 from the electrostatic latent image load is to carrying on a shoulder pole the distance on the surface of holding body (photoreceptor) with the electrostatic latent image of matrix material opposite one side.Therefore, as shown in Figure 2, when electrostatic latent image load was held body (photoreceptor) 3 and is made of barrier layer 41, photographic layer 42 and sealer, the thickness of photoreceptor be the value after the thickness of each layer total.

At Fig. 5, among Fig. 6, the 50th, developer reservoir, the 51st, the magnet drum of the expression of 1 among described Fig. 1, the 52nd, the developing roller of the expression of 2 among Fig. 1, the 53rd, held the paper feeding cassette of recording medium, the 54th, the travelling belt of recording medium, the 55th, the electrostatic latent image load of the expression of 3 among Fig. 1 is held body (being designated hereinafter simply as photoreceptor), the 56th, be used to the charged device that makes photoreceptor charged, the 57th, on photoreceptor 55, make the exposer of image exposure, the 58th, be used for that the toner on the photoreceptor 55 is looked like to copy to being used on the recording medium and add replica biased reproducing unit, the 59th, make the toner that copies on the recording medium fixing device as photographic fixing, in Fig. 6, the 60th, forming toner on each photoreceptor as overlapping, the intermediate duplication body that duplicates, 61 are used for the toner on the photoreceptor 55 is looked like to copy to the cylinder that duplicates on the intermediate duplication body 60, the 62nd, be used for the secondary that the toner on the intermediate duplication body 60 looks like to copy on the recording medium and duplicate cylinder, the 63rd, the clearer of intermediate duplication body, the 64th, development amount detection part, wherein, by photoreceptor 55, developing roller 52, magnet drum 51, charged device 56, exposer 57 grades constitute processing element.

Below, illustrate that these tandem type images form the action of device.The tandem type image that directly copies on the recording medium at the toner picture that forms on photoreceptor 55 shown in Figure 5 forms in the device, by at developer reservoir 50 (50 ₄～50 ₁) in hold by the developer that constitutes with corresponding toner of all kinds such as yellow, blue, red, black and carrier, at magnet drum 51 (51 ₄～51 ₁) on formed magnetic brush, by this magnetic brush, at developing roller (52 ₄～52 ₁) the last thin layer that forms toner.And if the control circuit that does not show from figure transmits the signal that begins to print, recording medium is sent from paper feeding cassette, delivers to travelling belt, cooperates this recording medium to arrive photoreceptor 55 (55 of all kinds ₄～55 ₁) timing, carry out based on charged device 56 (56 ₄～56 ₁) charged, based on sending to exposer 57 (57 ₄～57 ₁) on picture signal to photoreceptor 55 (55 ₄～55 ₁) exposure and the formation of latent image, based on developing roller (52 ₄～52 ₁) on the development of this latent image of toner, if recording medium arrives photoreceptor 55 (55 of all kinds ₄～55 ₁), then added based on reproducing unit 58 (58 ₄～58 ₁) replica biased, toner looks like to be copied on the recording medium.And this process is at each photoreceptor 55 ₄～55 ₁Carry out repeatedly successively, successively copying image of all kinds on recording medium, use the fixing device photographic fixing, paper is discharged.

In addition, after the toner picture that forms on photoreceptor 55 shown in Figure 6 copied on the intermediate duplication body 60 earlier, the tandem type image that copies to again on the recording medium forms in the device, and was identical with the situation of Fig. 5, by at developer reservoir 50 (50 ₄～50 ₁) in hold by the developer that constitutes with corresponding toner of all kinds such as yellow, blue, red, black and carrier, at magnet drum 51 (51 ₄～51 ₁) on formed magnetic brush, by this magnetic brush, at developing roller 52 ₄～52 ₁The thin layer of last formation toner.And, if the control circuit that does not show from figure transmits the signal that begins to print, just carry out based on charged device 56 (56 ₄～56 ₁) charged, based on sending to exposer 57 (57 ₄～57 ₁) on picture signal to photoreceptor 55 (55 ₄～55 ₁) exposure and the formation of latent image, based on developing roller (52 ₄～52 ₁) on the development of this latent image of toner, based on duplicating cylinder 61 (61 ₄～61 ₁) to the duplicating of intermediate duplication body 60, make each photoreceptor 55 ₄～55 ₁The toner picture of last formation is overlapping on the intermediate duplication body 60 that constitutes by intermediate duplication band etc., after if all toners look like to be copied to intermediate duplication body 60, recording medium is sent from paper feeding cassette, be sent to 2 duplicating positions with intermediate duplication body 60, added replica biasedly on the cylinder 62 duplicating for 2 times, toner looks like to be copied on the recording medium.Then, by fixing device 59 photographic fixing, paper is discharged.

Form in the processing element of device at the tandem type image of the present invention that constitutes like this, toner 5 is supplied on the magnet drum 1 by the developer reservoir that does not show from figure, the two-component developer that is made of toner 5, low resistance carrier 4-1, high resistance carrier 4-2 forms magnetic brush 10, by stirring, make toner 5 positively chargeds, and limited layer thickness by limiting scraper 9.And, because the potential difference (PD) between magnet drum 1 and the developing roller 2, this charged toner 5 moves to developing roller 2 one sides, forms the thin layer 6 have only toner on developing roller 2 because and the electrostatic latent image load hold direct current (DC) bias voltage 7a (V that adds between the body (photoreceptor) 3 _Dc1), exchange the overlapping bias voltage of (AC) bias voltage 7b, the toner 5 of this toner thin layer 6 flies to the electrostatic latent image load and holds on the electrostatic latent image that forms on the body (photoreceptor) 3, develops.After development, magnetic brush 10 contacts with toner thin layer 6 on the developing roller 2 on the magnet drum 1, by brush effect based on the difference of each cylinder, special devices such as removing scraper plate need not be set, just can easily reclaim and replace the toner 5 of toner thin layer residual on developing roller 26.

Low resistance carrier 4-1 is used to reclaim remaining toner residual on the developing roller 2, and in this example, having used specific insulation is 10 ⁶The ferrite carrier of Ω cm, saturated magnetization 70emu/g, mean grain size 35 μ m.Promptly, be necessary to use 10 in order to reclaim the residual toner that develops from developing roller ⁸Low-resistance carrier that Ω cm is following is used magnetic brush, on the bite between developing roller and the magnet drum securely the toner of electrostatic adhesion peel off.And, in order to improve,, just very effective if the saturated magnetization of low resistance carrier is set to the strong magnetic force more than the 67emu/g based on the fissility that on the bite between this developing roller and the magnet drum, forms the pole effect of magnetic brush.If the saturated magnetization of low resistance carrier is lower than 67emu/g, the pole effect when then reclaiming, get effect based on scraping of magnetic brush and descend, can't obtain effect of sufficient.At this moment,, preferably use the carrier of the following minor diameter of 40 μ m, improve the surface area of carrier in order to increase the contact point with toner.As strong magnetic force and low-resistance carrier, magnetic iron ore carrier, Mn class ferrite, Mn-Mg class ferrite etc. are arranged, can intactly use these carriers, also can be in the scope that does not improve resistance, it is carried out surface treatment after, re-use.

4-2 is electronegative for the high resistance carrier, it is the toner 5 that is used for retainer belt positive electricity, in this example, use surface aggregate body to cover the ferrite surface with ultra high molecular weight polyethylene, and adjusting agent with resistance handles, adhere to the problem of separating for toner and have tough surface property with coating, before end mechanical life of developer, the material that coating is not peeled off.Generally, when surface coating, the coating on surface is peeled off more than 20%, and then the chargeding performance to toner changes, when the developing method at this example, below 5 μ g, will be owing to charged bad, the image contamination that generation is dispersed based on toner is more than 20 μ g, will cause developing performance to descend, take place easily to select to develop etc.

This resistance carrier 4-2 is electronegative for making toner 5 charged particular importances, and when making toner 5 charged, when adding interchange (AC), also the toner from developing roller 2 being dispersed has inhibition.The low resistance carrier 4-1 that promptly pays attention to reclaiming is effective for suppressing afterimage (afterimage), but make toner 5 correctly charged, keeping does not have fuzzy aspects such as generation just difficult, when long-term operation, toner 5 disperses from the surface of developing roller 2, problems such as charged device and exposure component pollution can be made, so must use with high resistance carrier 4-2 with chargeding performance.

It is more than the 50 μ m that this high resistance carrier 4-2 preferably makes mean grain size, saturated magnetization is that the surface of the ferrite magnetic carrier of 60～200emu/g keeps polymerization catalyst, import ethylene gas, polymerization reaction take place, with weight average molecular weight Mw is that High molecular weight polyethylene more than 50000 forms surface coating, this coating amount is amount of polyethylene 1～5Wt%, and, by conducting particles its surface resistance is controlled at 10 ⁹Ω cm～10 ¹²The electrostatic latent image carrier of Ω cm.If resistance value is lower than 10 ⁸Carrier development and fuzzy might take place in Ω cm, if surpass 10 ¹²Degradation image quality aggravation under the image color then might take place in Ω cm.And, be electrode area 5cm in the resistance value of this expression ², load 1kg is provided with the carrier layer of the thickness of 0.5cm, adds the voltage of 1～500V on the electrode up and down, measure current value wherein after, the value of coming out converts.

About such high resistance carrier, for example the present patent application people opens the spy and proposes in the flat 10-142843 communique, have the carrier core of magnetic and covered the coating that constitutes by the High molecular weight polyethylene resin on the surface of this carrier core, the coating that should be made of the High molecular weight polyethylene resin is at least as outmost shell, contain charged adjustment agent, resistance adjustment agent, mobile adjustment agent, by various adjuvants being set, just can improving permanance and control charged on the High molecular weight polyethylene surface.And as high-resistance carrier, except described carrier, if can confirm permanance, then the carrier of having handled with resistance high treating agent also can use.

The recyclability of residual toner 5 and make the charged viewpoint of toner 5 from the developing roller 2, in the mixture ratio of described high resistance carrier 4-2 and low resistance carrier 4-1, all the ratio of the low resistance carrier 4-1 in the carrier 4 is suitable about 50%～80%.If below 50%, just can't fully reclaim toner 5, cause the generation of afterimage, if more than 80%, just can't prevent dispersing of toner 5.

In addition, the blending ratio of the toner 5 in this example is for the total amount of carrier 4 and toner 5, and toner 5 is 2～40 weight %, is preferably 3～30 weight %, is preferably 4～25 weight %.If promptly the blending ratio of toner is lower than 2 weight %, then the carried charge of toner 5 raises, and can't obtain sufficient image color, if surpass 40 weight %, then can't obtain sufficient carried charge, toner disperses from developer, pollution image forms device inside, or forms fuzzy on image.

With certain ratio combination both sides' carrier, just can reclaim the toner 5 of the toner layer thin layer 6 on the developing roller by like this, just can put into charged exactly toner 5 on the developing roller once again.Toner 5 is controlled in 5～20 μ C/g, just can prevent dispersing, bluring of toner, and, by under low-voltage, developing, the hysteresis phenomenon of just on developing roller, not developing, thus can be provided at image processing system superior in the recovery of toner 5.

Hold the surface potential (charged current potential) of body (photoreceptor) 3 about electrostatic latent image load, below the 25V, and be set to below the 100V, make the current potential that is added on the developing roller 2 low, and can obtain sufficient image color by the afterpotential that exposes.Hold body (photoreceptor) 3 as using the electrostatic latent image load in the image processing system, the Organophotoreceptor (OPC) that positively charged is just arranged all the time, when electrostatic latent image load was held body (photoreceptor) 3 and used this Organophotoreceptor (OPC), the addition that increases charge generating material was important.Particularly the Organophotoreceptor of single layer structure (OPC) has added charge generating material in photographic layer, so favourable.

But the photographic layer soft surface of OPC photoreceptor is because the friction of cleaning balde makes the photographic layer wearing and tearing easily.At this, compare with the OPC photoreceptor, the surface hard and aspect permanance and function retentivity (non-maintaining) superior performance, so what use in recent years is that the thickness of photographic layer is the a-Si photoreceptor of 25 μ m.But, because the a-Si photoreceptor is to use film forming such as electric glow discharge method, thus if photographic layer is thick like this, can cause manufacturing time long, the manufacturing cost height, very uneconomical.At this, the present patent application people opens in the flat 7-175276 communique the spy, and the thickness that has proposed photographic layer is set to the a-Si photoreceptor of discontented 25 μ m.

When holding in the body (photoreceptor) 3, when having used the a-Si photoreceptor, have the low-down feature of exposure afterpotential below 10V on its surface as photosensitive material in the electrostatic latent image load, but, if its thickness attenuation, then the saturated zone electric potential descends, the withstand voltage decline of insulation breakdown.On the one hand, the electric density that the electrostatic latent image load when forming latent image is held the surface of body (photoreceptor) 3 improves, and the tendency of developing performance raising is arranged.In specific inductive capacity is about 10 high a-Si photoreceptor, below 25 μ m, be preferably in 20 μ m when following, this characteristic is remarkable especially.

But if the thickness of photographic layer 42 is lower than 10 μ m, then electrostatic latent image is carried on a shoulder pole the current potential of holding body (photoreceptor) 3 and is regulated the difficulty that becomes, and so-called stain and fuzzy takes place easily.In addition, if the thickness of photographic layer 42 is lower than 10 μ m, then the saturated zone electric potential descends, and the tendency that can't guarantee necessary charged current potential is arranged.And if the thickness of photographic layer 42 surpasses 25 μ m, then the electronegative potential difficulty that becomes of developing is easy to generate ozone, or makes the manufacturing time of photographic layer elongated etc., causes economically unfavorable easily.Move to photographic layer surface institute in the hole that the charge generation layer of photographic layer 42 produces and take time elongatedly, regulate the difficulty that becomes, so-called fuzzy, image color takes place easily descend the degradation problem easily so the electrostatic latent image load is held the current potential of body (photoreceptor) 3.Therefore, if treat that the current potential of holding body (photoreceptor) 3 with electrostatic latent image load is regulated and the balance of economy etc. from more superior viewpoint, the thickness that then should make the electrostatic latent image load hold the photographic layer 42 of body (photoreceptor) 3 is 11～25 μ m, is preferably the interior value of scope of 12～18 μ m.

In addition, as the state of better photographic layer 42, the thickness that should make sealer 43 is the value that 0.3 μ m is above, 5 μ m are following.If promptly the thickness of sealer 43 is lower than 0.3 μ m; then the saturated zone electric potential of photographic layer 42, mar proof, environment resistant etc. characteristic have the tendency of decline, and if the thickness of sealer 43 surpasses 5 μ m, then cause image quality aggravation; and manufacturing time is elongated, and is unfavorable economically.Therefore, from the balance of the saturated zone electric potential of better viewpoint balance photographic layer 42 and manufacturing time etc., the thickness that preferably makes sealer 43 is the values in 0.3 μ m～3 mu m ranges.

Constitute the material of photographic layer 42, if amorphous silicon (a-Si), just be not limited to specificly,, inorganic material such as a-Si, a-SiC, a-SiO, a-SiON are arranged as best material.In addition, sealer 43, a-SiC resistance is high especially, has better saturated zone electric potential, mar proof, environment resistant, so be suitable as the photographic layer material of this example.In a-SiC, what preferably use is that the ratio of Si and C (carbon) is specific, as such a-SiC, a-Si _1-xC _x(0.3≤X≤1.0) are preferably a-Si _1-xC _x(0.5≤X≤0.95).This be because, have extra high resistance among such a-SiC, reach 10 ¹²Ω cm～10 ¹³Ω cm just can obtain superior saturated zone electric potential, mar proof, environment resistant (moisture-proof).

Developing roller 2 and electrostatic latent image load is held bias voltage between the body (photoreceptor) 3 by dc bias power 7a (V _Dc1), AC bias power supply 7b decision, still, in order on magnet drum 1, to reclaim the development residual toner efficiently, bias voltage 8 (V _Dc2) current potential be preferably in below the 500V.If with dc bias power 7a (V _Dc1) adding the above voltage of 150V, toner increases attached to the electrostatic force on the developing roller 2, is difficult to reclaim with magnetic brush.In addition, if add alternating electric field with AC bias power supply 7b, its advantage is can correctly carry out carrying on a shoulder pole the development of holding body (photoreceptor) 3 to electrostatic latent image, just can easily reclaim the development remaining toner to magnet drum 1.

Fig. 3 has represented not produce afterimage (afterimage) and fuzzy good development Dc bias current potential 7a (V in the developing parts of this example _Dc1), 8 (V _Dc2) scope.Transverse axis is represented potential difference (PD) | V _Dc2-V _Dc1|, the longitudinal axis is represented bias (V _Dc1).And, as shown in Figure 3, if bias (V _Dc1) be higher than 150V, produce dual imaging, if | V _Dc2-V _Dc1| be lower than 100V, also produce dual imaging.Therefore, as the Dc bias current potential 7a (V of developing roller 2 _Dc1) be below the 150V, and, the Dc bias current potential 8 (V of magnet drum 1 _Dc2) and the Dc bias current potential 7a (V of developing roller 2 _Dc1) potential difference (PD) | V _Dc2-V _Dc1If | in the scope of 350V, just can obtain high-quality image quality, at 100V as 2 interchange that adds (AC) grid bias power supply 7b on developing roller, voltage (V between its peak value _P-p) be 500～2000V, frequency is 1～3kHz.

Like this, be provided with the development bias voltage lowly, not only the electrostatic latent image load is held the insulation breakdown of the a-Si film of body (photoreceptor) 3 always, and prevents the superfluous charged of toner 5, and for the hysteresis phenomenon that suppresses to develop is effective.In addition, on developing roller 2, form 10～100 μ m, the toner thin layer 6 of 30～70 μ m preferably, the gap that makes developing roller 2 and electrostatic latent image load hold body (photoreceptor) 3 is 150～400 μ m, is preferably 200～300 μ m, like this can be by direct current and AC field, make toner fly to the electrostatic latent image load and hold on the body (photoreceptor) 3, thereby can obtain distinct image.

Limiting scraper 9 and magnet drum 2 be 0.3～1.5mm gradually, the gap between magnet drum 1 and the developing roller 2 is similarly about 0.3～1.5mm.By like this, the thin layer 6 of the toner on the developing roller is set to 10～100 μ m, is preferably the thickness of 30～70 μ m.When the mean grain size of toner 5 was 7 μ m, this thickness was the value that is equivalent to 5 layers～10 layers of toner 5.The gap that developing roller 2 and electrostatic latent image load are held between the body (photoreceptor) 3 is 150～400 μ m, is preferably 200～300 μ m.If be lower than 150 μ m, can cause bluring, if be higher than 400 μ m, then be difficult to make toner 5 to fly to the electrostatic latent image load and hold on the body (photoreceptor) 3, just can't obtain sufficient image color.In addition, become the reason of selecting development.

And, in this example, an image developing when making a plurality of image of continuous each processing element of formation, to the beginning next image development before non-image formation during or before beginning to form image, make described developing roller 2 and magnet drum 1 keep rotation, produce the equal equipotential state of current potential that makes between two cylinders, and, under these potential state states, reclaim the afterimage toner of the toner thin layer 6 on the described developing roller 2 with magnetic brush 10.

And, for example can detect non-image formation according to the printed image data of delivering to exposer 57 during, for example in paper feeding cassette 53, also can detect from the top and the rear end of recording medium.

And, be that the a-Si of 15 μ m constitutes the electrostatic latent image load and holds body (photoreceptor) 3 with bed thickness, surface potential is 230V, the Dc bias 7a (V that adds to developing roller 2 _Dc1) be 50V, exchanging (AC) bias voltage 7b is voltage (V between peak value _P-p) be 1.1kV, frequency is 3.0kHz, the Dc bias 8 (V that add to magnet drum 1 _Dc2) be 200V, as mentioned above, during non-image formation, the surface potential of developing roller 2 (is Dc bias 7a (V _Dc1)) and the surface potential of magnet drum 1 (be Dc bias 8 (V _Dc2)) be 0V all, produce equipotential state.And as shown in Figure 4, the stereo-picture that is made of the rectangle black surround with continuous formation and than the image model of the half tone image of this stereographic map image width forms image, at this moment, estimates the afterimage of the stereo-picture that whether has formed black surround.At this, the concentration of half tone image is 25% of stereo-picture concentration, if but like this, than being easier to form afterimage.

And, as a comparative example, during non-image formation, neither the equipotential state, at first, and as a comparative example 1, and form same bias voltage during the image, promptly as the Dc bias 7a (V that adds to developing roller 2 _Dc1) be 50V, exchanging (AC) bias voltage 7b is voltage (V between peak value _P-p) be 1.1kV, frequency is 3.0kHz, the Dc bias 8 (V that add to magnet drum 1 _Dc2) when being 200V, as a comparative example 2, during non-image formation, make the bias voltage of developing roller 2 and magnet drum 1 is put upside down, be i.e. the Dc bias 7a (V that adds to developing roller 2 _Dc1) be 200V, do not add interchange (AC) bias voltage 7b, the Dc bias 8 (V that add to magnet drum 1 _Dc2) when being 50V, confirmed concentration, afterimage and the fuzzy generation of three phases such as original state, the 100th, the 1000th.Its result is as shown in table 1.

Table 1

	Initially			100			1000
										Concentration	Afterimage	Fuzzy	Concentration	Afterimage	Fuzzy	Concentration	Afterimage	Fuzzy
	Embodiment	○	○	○	○	○	○	○	○										○
Comparative example 1										○	○	○	○	△	○	△	×	○
	Comparative example 2	○	○	○	○	○	△	○	○										×

And, in this table 1, " zero " on concentration hurdle is not fuzzy in the image of representing to form, " △ " expression has a point fuzziness, picture pattern shown in Figure 4 prints, when shown in (a) in " zero ", " △ ", " * " in afterimage and fuzzy hurdle, on half tone image, when not observing afterimage or afterimage fully, be zero, shown in (b), on half tone image, in the time of observing afterimage or afterimage a little, be △, in addition, in the time of just clearly confirming, for *.

As known from Table 1, in an embodiment, in any one of initial, three phases such as the 100th, the 1000th, all not have to find bluring on concentration, afterimage and fuzzy generation, just can form preferable image.In contrast to this, in comparative example 1, because all adding same bias voltage during the non-image formation and during forming image, so accumulated afterimage gradually, its result is at the 100th, afterimage can be observed a little, and, just afterimage can be clearly confirmed the 1000th stage.In comparative example 2, because added the bias voltage that the potential difference (PD) during the non-image formation is put upside down, though can suppress the generation of afterimage, but the charged variation of toner takes place to blur, at the 100th, can observe fuzzyly a little, and, just can clearly confirm to blur the 1000th stage.Therefore, from result shown in the table 1 as can be known,, just can avoid the generation of bluring, just can suppress the generation of afterimage, thereby can form distinct image by during non-image formation, taking the equipotential state.

And, in the explanation of described example, in this example, for example be to be equipotential during the non-image formation when making a plurality of image of continuous formation, still, this can be to be equipotential during the non-image formation that makes before beginning to form image, in addition, making developing roller 2 and magnet drum 1 equipotential current potential is 0V, still, as long as it is just passable that two surface potentials are equal to each other, for example be respectively 50V.In addition, these potential states can be realized by two surface potentials of control developing roller 2 and magnet drum 1, also can make the surface potential of a side and equating of opposite side by control, also can not be to be the equipotential state during whole during the non-image formation, can be to be the equipotential state in during the part.

In addition, when the extremely low image of continuous printing lettering rate and when only printing specific look, charged the going up of developer economized, the development amount of toner can change, but, in the present embodiment, before causing image change, the toner of deterioration is discharged from processing element, just can obtain stable coloured image.

With the CPU (not shown) in the tandem type image formation apparatus main body, view data is carried out instrumentation as counting, measure the original copy density a on the image _n, the original copy density a1 of every recording medium of mensuration, a2, a _N3... a _nAverage original copy density A be lower than 3[%] time, end image and form, enter during the non-image formation, on developing roller 2, add the renewal process of alternating electric field, make the toner on the developing roller 2 fly to photoreceptor 3 one sides, consumption.In addition, in this example, the situation when ending image at once forms has been described, when printing continuously, also can have carried out after the printing end continuously.

Developing roller 2 has the surface of having carried out based on the setting or the inject process of unsetting particle, as alternating electric field, is overlapping square wave, triangular wave, sinusoidal wave AC composition in dc voltage.The calculation of image character-display unit, be when each printing, to carry out, calculate certain number (for example 1～500 's) average lettering number, according to character-display unit, when on photoreceptor 3, not forming image (during non-image formation), or after the driving of photoreceptor 3 and developing roller 2 stops, toner is circled in the air from developing roller 2, carry out the consumption of toner.And, by this renewal process, form in the device at the tandem type image that does not use the intermediate duplication body shown in Figure 5, when described non-image formation, swept on the recording medium from photoreceptor 3 attached to the toner on the photoreceptor 3, and in use shown in Figure 6 the tandem type image of intermediate duplication body 60 form in the device, swept on the intermediate duplication body 60, discarded by intermediate duplication body and function clearer 63.

In a word, calculate average lettering rate after, when photoreceptor 3 and developing roller 2 are in driving condition, carry out the control of alternation bias voltage, carry out the consumption of toner.And, from test, confirmed when average lettering rate 3% when following, the charging of toner takes place easily.In addition,, increase, be necessary to increase adding the time of the alternation bias voltage that is used to peel off this remaining toner, make the developing roller rotation repeatedly, increase the amount of the toner that flies to the photoreceptor magnetic drum in the amount of the remaining toner of developing roller 2 if average lettering rate descends.

Therefore, about the consumption of toner of described non-image portion, minimum is equivalent to 3% original copy lettering, still, preferably by having multiple more new model, just can be provided with, and makes it can take to be suitable for the correspondence of situation (environment for use etc.).In addition, in renewal process, the effective value of the alternating electric field when making the effective value that upgrades with alternating electric field be higher than image formation just can easily consume toner.

And, at this moment, in described renewal process, for the toner that copies on the intermediate duplication body 60, be determined as the definite toning dosage of each color by development amount detection part 64 and be developed,, just can detect the deterioration state of toner simultaneously by measuring the development amount of the toner of forcing consumption.In addition, when copying to toner on the intermediate duplication body 60, when having a plurality of processing element that does not reach given development amount, by state with colour superimposition for renewal, copy to the same part of the non-pass-through area on the intermediate duplication body, just can carry out this renewal at a high speed.

In addition, as mentioned above, when the extremely low image of continuous printing lettering rate and when only printing specific look, the charged rising of toner, the development quantitative changeization of toner, but when toner charged (below, be called Q/M) when rising, because toner securely electrostatic adhesion on the surface of carrier 4, so the spy opens the 2000-112220 communique, the spy opens the output valve of describing in detail in the 2000-112221 communique based on the magnetoconductivity of the developer of toner concentration (T/C) sensor and descends, if Q/M descends, then peel off toner and become simply, so magnetoconductivity rises from carrier surface.

In being installed in developer reservoir fixedly installing and be spiral helicine screw type stirring apparatus around the turning axle that can rotate freely, or the bottom that is provided with the stirring apparatus (single oscillating mode stirring apparatus) etc. of a plurality of blades that tilt with axially parallel on such turning axle is provided with described spy and opens the 2000-112220 communique, the spy drives the magnetoconductivity sensor of describing in the 2000-112221 communique that is used to measure toner concentration, because in the magnetic rotation of this stirring apparatus, developer level on this magnetoconductivity sensor changes, so pulsation shown in Figure 7 takes place, but, if the Q/M of toner rises, as mentioned above, because toner securely electrostatic adhesion on the surface of carrier 4, so the magnetoconductivity of magnetoconductivity sensor descends, if Q/M descends, then peel off toner and become simple from carrier surface, so as 72, magnetoconductivity rises.

But in the mixing of above explanation was developed, particularly when printing continuously, toner was rubbed by magnetic brush on one side, Yi Bian added bias voltage, so the toner Q/M of the toner thin layer 6 that forms on developing roller 2 rises easily.And, the supply of toner is the value rising at the magnetoconductivity sensor, carry out during the density loss of toner, if but the Q/M of toner rises, as mentioned above, the output of the magnetoconductivity of magnetoconductivity sensor descends, although because printing has consumed toner, but magnetoconductivity has shown low value, and the toner concentration (T/C) that causes estimation is than actual height, the toner of not supply temporarily.

Therefore, in this example, as mentioned above, by form the CPU (not shown) in the apparatus main body with tandem type image, view data is carried out instrumentation as counting, read the lettering rate, calculate the consumption of toner, infer, when detecting the toner concentration of the value lower than the toner concentration of reality, carry out described renewal process, scan out toner.

Now, with the lettering rate of counting and calculating according to described instrumentation, be C by the consumption of toner that calculates the given number of inferring, the mean value during the stirrer week of the simulation output of described toner concentration sensor is that Tave is (if Q/M rises, then descend), initial average output value is Tini.At this moment,

ΔT＝Tini-Tave (1)

Consumption toning dosage D for the total carrier amount in the developer is:

D=C/ (the total carrier amount in the developer) * 100 (%) (2)

When D＞1 (%), when

(i)ΔT≥0.2V

The time, as mentioned above, make developing roller 2 and magnet drum equipotential, as the block diagram picture is developed, toner is swept to the pattern that scans out on the intermediate duplication body energetically on photoreceptor 3; As (ii) 0V＜Δ T＜0.2V

The time, as the pattern that only scans out some toners, for example, half tone image or line map are developed; When

(iii)ΔT≥0V

The time, as toner deterioration, be the pattern of changing toner container.

And, the coefficient of counting in this control is when the driving of supply motor stops, calculate by the CPU (not shown) that described tandem type image forms in the apparatus main body, when the driving of having carried out the supply motor, supply during toner, described toner concentration sensor (magnetoconductivity sensor) detects this supply, removes described Tini value, C value, D value, repeats same work then.

Like this, by control toner Q/M, as shown in Figure 8, just can in the passing of Q/M, observe significant difference.Promptly in this Fig. 8, X-axis is the printing number, Y-axis is toner Q/M (μ C/g), the 80th, charged (Q/M) amount of the toner when having carried out above-mentioned control, the 81st, charged (Q/M) of the toner when not carrying out above-mentioned control amount is though when not carrying out above-mentioned control, charged (Q/M) amount of toner rises, but when controlling, charged (Q/M) of toner measures significantly within the specific limits.

Therefore, according to this example, by during non-image formation or before beginning to form image, make described developing roller and magnet drum keep rotation, the equipotential state that generation equates the current potential between two cylinders, the magnetic brush that forms on the magnet drum has all reclaimed the toner on the developing roller, having eliminated the development on the developing roller lags behind, suppress afterimage and fuzzy generation, so can provide charged exactly toner for developing roller, just can constitute small-sizedly, in view of the above, just can constitute small-sized series connection image processing system obtaining the processing element of stable image quality for a long time.

In addition, according to this example, when being lower than specified rate by consumption of toner in described each processing element, forcibly toner is discharged to recording medium or the intermediate duplication body from processing element, when printing the extremely low image of lettering rate continuously or only printing specific color, just can prevent the charged rising of developer, the development amount of toner changes, toner deterioration before causing image change is discharged from processing element, just can obtain stable coloured image, just can constitute small-sizedly, in view of the above, just can constitute small-sized series connection image processing system obtaining the processing element of stable image quality for a long time.

According to this example, when the extremely low image of continuous printing lettering rate or when only printing specific color, charged (Q/M) that just can prevent toner rises, electrostatic adhesion is on the surface of carrier 4 securely, magnetoconductivity output valve based on the developer of toner concentration (T/C) sensor descends, the developer toner use amount than reality that causes estimating is lacked, and not supply toner, thereby can constitute and small-sized can obtain the processing element of stable image quality for a long time, in view of the above, just can constitute small-sized series connection image processing system.

In addition,, not only can hold discharge rate according to this example, and, even, also can carry out this control at short notice when a plurality of processing element are discharged toner.

According to relevant example, need not make the developing parts complexity, the generation of the afterimage in the time of just preventing to develop continuously, for developing roller provides charged exactly toner, just can constitute and small-sized can obtain the processing element of stable image quality for a long time, in addition, when printing the extremely low image of lettering rate continuously or only printing specific color, just can prevent the charged rising of developer, the development amount of toner changes, toner deterioration before causing image change is discharged from processing element, can obtain stable coloured image.

Fig. 3 has represented not produce Dc bias current potential 7aV on afterimage (afterimage) and the fuzzy good developing roller 2 in the developing parts in the developing apparatus of this example _Dc1Dc bias current potential 8V with magnet drum 1 _Dc2Scope.Transverse axis is represented potential difference (PD) | V _Dc2-V _Dc1|, the longitudinal axis is represented the bias V of developing roller 2 _Dc1And, as shown in Figure 3, as bias V _Dc1When being higher than 180V, | V _Dc2-V _Dc1| when being lower than 100V, produce afterimage (afterimage).In addition, if this potential difference (PD) more than 350V, toner disperses, and takes place fuzzy.Therefore, if as the Dc bias current potential 7aV on the developing roller 2 _Dc1Below 180V, and the Dc bias current potential 8V of magnet drum 1 _Dc2With the development Dc bias current potential 7aV on the developing roller 2 _Dc1Potential difference (PD) | V _Dc2-V _Dc1| arrive in the scope of 350V 100, just can obtain high-quality image quality.And, the voltage of 2 interchange that adds (AC) grid bias power supply 7b on the developing roller is set, make voltage V between its peak value _P-pBe 500～2000V, frequency is the scope of 2～4kHz, produces positive dutycycle when using the positively charged toner less than 45%, and when the electronegative toner of use, negative dutycycle is less than 45% square wave.Like this, by being provided with the development bias voltage lowly, the improper electrostatic latent image load that can suppress is held the insulation breakdown of the a-Si film of body (photoreceptor) 3, and can prevent the superfluous charged of toner 5, thereby suppresses the generation of the hysteresis phenomenon of development effectively.

Two-component developer forms toner 5 and is made of carrier 4 on magnet drum magnetic brush 10 makes toner 5 charged by stirring.This carrier 4 uses the surface aggregate body with ultra high molecular weight polyethylene to cover the ferrite surface, and adjusting agent with resistance handles, adhere to the problem of separating for toner and have tough surface property with coating, before end mechanical life of developer, the material that coating is not peeled off.Generally, when being the surface coating carrier, if the coating on surface is peeled off more than 20%, then the chargeding performance to toner changes, when using this example developing method, found the generation of the image contamination of dispersing and the decline of development based on toner, so-called selection development etc. has taken place.Therefore, guarantee that the durable stability of carrier is important, as mentioned above, use the polymerization of not peeling off by coating before finishing the mechanical life with developer, adjusted the carrier of surface resistance in ferrite surface coverage high-molecular polythene coating.

In the developing apparatus of the image processing system of this example that constitutes like this, the two-component developer that is made of toner 5, carrier 4 is supplied on the magnet drum 1 by the developer reservoir that does not show from figure, by stirring these developers, make toner 5 positively chargeds, form magnetic brush 10, limited layer thickness by limiting scraper 9.And, this charged toner 5 because 1 and developing roller 2 between potential difference (PD) | V _Dc2-V _Dc1|, move to developing roller 2 one sides, on developing roller 2, form the thin layer 6 have only toner, by and the electrostatic latent image load hold add between the body (photoreceptor) 3 by direct current (DC) bias voltage 7a (V _Dc1), with the bias voltage that (AC) bias voltage 7b obtains after overlapping that exchanges that produces square wave, fly to the electrostatic latent image load and hold on the electrostatic latent image that forms on the body (photoreceptor) 3, develop.

And, in the present invention, before and after image forms, and between image formation and the formation of image next time, or during the non-image formation between the recording medium when forming image continuously etc., make described developing roller and magnet drum keep rotation, make the potential difference (PD) between described first and second Dc biases produce the equipotential state, and, the AC field that formation is made of square wave, magnetic brush 10 on the magnet drum 1 is contacted with toner thin layer 6 on the developing roller 2, after development, replace at the toner that remains in after the development on the developing roller 2 with magnetic brush 10 and AC bias.Therefore, the charged distribution of the toner of recovery is broadened, or it is changed,, the special device of removing scraper plate etc. need not be set, just can easily reclaim and replace toner only by brush effect based on the difference of each cylinder.

And, when also comprising the starting of the described machinery that on developing roller, does not develop in addition during the non-image formation, for the detection during this non-image formation, can make image hold the printed image data of the exposer of exposure on the body (photoreceptor) 3 in the electrostatic latent image load according to for example sending to, detect, also can detect according to the top and the rear end of the recording medium of the paper feeding cassette that has held recording medium.In addition, in this example, during the non-image formation when forming image continuously in, replaced all toners on the developing roller 2, so make the length between recording medium also longer than the processing girth of described developing roller 2 by control.In this example,, should make the rotational speed of described magnet drum 1 be at least more than 1.0 times of rotational speed of developing roller 2 for the replacement that makes toner becomes easily.

Like this, the recovery and the replacement of the toner on the developing roller 2 have been carried out, if but fully do not carry out this replacement, shown in Fig. 4 (b), the part corresponding with the stereo-picture that develops earlier 13 can not be developed when the development that the electrostatic latent image load of following is held body fully, produces afterimage (afterimage) 44 on half tone image 16.Promptly as shown in Figure 4, if be configured to the stereo-picture 13 that constitutes by the rectangle black surround and follow developing continuously of it than its wide half tone image 16, if the recovery of toner and replacement are carried out insufficiently, shown in Fig. 4 (b), can stay afterimage 14A in the part corresponding with the block diagram picture that develops earlier.

In the processing element that constitutes like this, as shown in table 1, during the non-image formation of (between paper) between recording medium and recording medium, making the surface potential of developing roller 2 (is Dc bias 7aV _Dc1With exchange (AC) power supply 7b) and the surface potential of magnet drum 1 (be Dc bias 8V _Dc2) various variations take place, confirm image with the model machine of 12 machines, estimate.During this is estimated, form image with the stereo-picture 13 that is configured to constitute with than the picture patterns that the half tone image 16 of this stereographic map image width develops continuously by rectangle black surround shown in Figure 4, check this moment concentration, whether afterimage 14A, the fringe of the stereo-picture of black surround have appearred, be summarized as table 3.Printing blank sheet of paper pattern is checked the situation occurred that adheres to developing roller 2, is summarized as table 4.And the diameter of the developing roller 2 of the model machine of 12 machines is 16mm, girth 50.24mm.And the recording medium during the non-image formation and the interval of recording medium (paper at interval) are 51mm, therefore, in this paper interval, just can carry out the replacement of the toner of developing roller one circle.

The condition of this evaluation is: hold body (photoreceptor) 3 as the electrostatic latent image load, use the a-Si of bed thickness 14 μ m, surface potential 250V, the Dc bias 7aV on the developing roller 2 _Dc1Be 50V, voltage V between the peak value of interchange (AC) bias voltage 7b _P-pBe 1.3kV, frequency is 3.0kHz, and dutycycle is 50%.In addition, be applied to the Dc bias 8V of magnet drum 1 _Dc2Be 200V, the difference between magnet drum 1 and the developing roller 2 is 2 times, and the rotational speed of magnet drum 1 is fast.And as embodiment 1～3, during the non-image formation of (paper at interval) between recording medium and the recording medium, making the surface potential of developing roller 2 (is Dc bias 7aV _Dc1) and surface potential (the Dc bias 8V of magnet drum 1 _Dc2) all be 0, produce the equipotential state, and added by voltage V between peak value _P-pBe 1.3kV, the AC field that the square wave that dutycycle changes at three phases such as 40,45,50% constitutes.In addition, as a comparative example, do not add interchange, making the surface potential of developing roller 2 (is Dc bias 7aV _Dc1) when being 50V (comparative example 1), during for 200V (comparative example 2).

Table 2

	Photoreceptor	Surface potential	The V1 developing roller	The V2 magnet drum	Difference magnet drum/developing roller	Current potential between paper
							Embodiment
1	a-Si 14μm	250V	V dc1：200V V pp：1.3kV Duty：50％ F：3kHz	V dc2：200V	2 times	V dc1＝V dc2＝0V V pp：1.3kV Duty：50％
							Embodiment
2	↑	↑	↑	↑	↑	V dc1＝V dc2＝0V V pp：1.3kV Duty：45％
							Embodiment
3	↑	↑	↑	↑	↑	V dc1＝V dc2＝0V V pp：1.3kV Duty：40％
							Comparative example 1	↑	↑	↑	↑	↑	V dc1＝50V V dc2＝0V V ppDo not add
Comparative example 2	↑	↑	↑	↑	↑	V dc1：＝200V V dc2＝0V V ppDo not add

And, concentration, afterimage and the fuzzy generation in the concentration shown in the table 1, afterimage, fuzzy evaluation, having confirmed original state, printed the 100th, printed three phases such as the 1000th.In this table 2, " zero " on concentration hurdle is not fuzzy in the image of representing to form, and " △ " expression has a point fuzziness.In " zero ", " △ " in afterimage and fuzzy hurdle, " * ", print picture pattern shown in Figure 4, when shown in (a), on half tone image, when not observing afterimage or afterimage fully, be zero, shown in (b), on half tone image, in the time of observing afterimage or afterimage a little, be △, in addition, in the time of just clearly confirming, for *.

Table 3

	Initially			100			1000
										Concentration	Afterimage	Fuzzy	Concentration	Afterimage	Fuzzy	Concentration	Afterimage	Fuzzy
	Embodiment
1		○	○	○	○	○	○	○	○	○
	Embodiment 2										○	○	○	○	○	○	○	○	○
Embodiment 3		○	○	○	○	○	○	○	○	○
	Embodiment 4										○	○	○	○	○	○	○	○	○
Comparative example 1		○	○	○	○	△	○	△	×	○
	Comparative example 2										○	○	○	○	○	△	○	○	×

As known from Table 3, shown in comparative example 1, when the paper interval, an external dc bias voltage disconnects under the state of AC field, and afterimage increases gradually.In addition, in the comparative example 2 that has added Dc bias energetically, though can suppress afterimage, fuzzy generation has been found in the charged variation of toner.And make DC electric field is 0 or minimum, on developing roller, added among the embodiment 1～3 of alternating voltage, because AC field has been replaced the toner on the developing roller efficiently, even so in printing the 1000th the time, concentration, afterimage, fuzzy etc. several all be good.

And, at printing blank sheet of paper pattern, investigated toner in the table 3 of the situation occurred that adheres to of developing roller 2, checked original state, printed 100, printed 1000, printed in the four-stages such as 10000 toner to the situation of adhering to of developing roller 2.In this table 3, " zero " expression does not observe toner adhering to developing roller 2 fully, the state that " △ " expression is adhered to thinly, " * " is illustrated in toner and adheres to developing roller 2 comprehensively, expression has taken place because toner disperses, the state that the pollution, toner that causes the developing roller bottom falls from developer etc.

Table 4

	Initially	100	1000	3000	10000
						Embodiment 1	○	○	○	△	△
Embodiment 2	○	○	○	○	△
						Embodiment 3	○	○	○	○	○
Comparative example 1	○	△	×	×	×
						Comparative example 2	○	○	○	×	×

As known from Table 4, in comparative example 1, when having printed 100, on developing roller 2, adhere to one deck toner thinly, after having printed 1000, on developing roller, adhered to toner comprehensively.This is because of the toner of almost not replacing on the developing roller.Because the toner that adheres to is irrelevant with development, always stay on the developing roller, so the new carried charge of falling the toner on it descends, become the reason that toner disperses.In addition, because the carried charge of toner descends, the concentration of attachment portion raises.In addition, because the resistance of the toner that adheres to causes the thickness attenuation of the toner layer relevant with the development on the developing roller, show dual imaging (afterimage) significantly.After having printed 10000, owing to dispersing of toner, pollution, toner that the developing roller bottom has taken place significantly fall from developer.

In comparative example 2, though printing after 100,1000, do not find fully to adhere to, in the moment of having printed 3000, found comprehensively adhering to developing roller.If the toner carried charge in the mensuration two-component developer then is to drop to 5 μ C/g after the carried charge of 16 μ C/g has printed 3000 in initial, the thickness of the toner layer on the developing roller is also from 1.4 initial～1.6mg/cm ²Be increased to 2.5～2.8mg/cm after having printed 3000 ²In addition, the toner carried charge of just having measured in the two-component developer distributes, and when initial, is 2.2 ± 0.5fC/ μ m, 90% frequency, after having printed 3000, becomes 0.7 ± 0.5fC/ μ m, 50% frequency, has broadened.This is because as mentioned above, by from developing roller toner being recovered to magnet drum one side with higher Dc bias, the toner in the lower two-component developer of the toner of the high-band electric weight on the developing roller and carried charge mixes suddenly.

And in embodiment 1～3, do not adhere to from initially finding fully when having printed 1000.Open the beginning from 3000, variation has taken place in situation, and aspect the adhering to of toner, embodiment 2 is better than the result of embodiment 1, and embodiment 3 is better than embodiment 2.From this result as can be known, drop to below 45% (because use the toner of positively charged by the dutycycle that makes the alternating voltage that constitutes by square wave that on developing roller 2, adds, so be positive dutycycle), the replacement of the toner on the developing roller 2 improves, and has alleviated toner adhering to developing roller 2.

Like this, before and after the printing and between the printing, under the state of magnet drum 1 and developing roller 2 rotations, make between developing roller 2 and the magnet drum 1 and do not have DC potential difference, by add dutycycle on developing roller 2 is 50% alternating voltage, the replacement of the toner on the developing roller 2 is improved, particularly from the embodiment 3 of table 1 as can be known, preferably make dutycycle less than 45%.In view of the above, just can solve toner to the adhering to of developing roller 2, development dual imaging, toner problem such as disperse.

In addition, in the explanation of described example, although understand that the equipotential current potential of developing roller 2 and magnet drum 1 is 0V, but just passable as long as two surface potentials are equal to each other, can be respectively 50V for example.In addition, these potential states can be realized by two surface potentials of control developing roller 2 and magnet drum 1, also can make the surface potential of a side and equating of opposite side by control, also can not be to be the equipotential state during whole during the non-image formation, can be to be the equipotential state in during the part.

According to this example, during non-image formation, make developing roller and magnet drum keep rotation, the equipotential state that generation equates surface potential, by only adding AC bias, only just all do not reclaimed the toner on the developing roller with magnetic brush, pass through AC bias, in the replacement of the toner in toner that has promoted developing roller and magnetic brush, also make when replacing the carried charge of the toner almost no change that distributes.

In addition, according to this example, the AC bias that adds on developing roller is a square wave, positive dutycycle when using the positively charged toner is less than 45%, when using electronegative toner, negative dutycycle is less than 45%, just can make the replacement of the toner on the developing roller become good, just can solve toner adhering to developing roller 2, the development dual imaging, problems such as toner disperses, as mentioned above, need not make developing apparatus complicated, the generation of the afterimage in the time of just preventing to develop continuously just can offer developing roller to charged exactly toner.

In addition, according to this example, make the length between recording medium also wideer by control than the processing girth of described developing roller, between recording medium, also can promote the replacement of the toner in the toner and magnetic brush on the described developing roller, even when printing continuously, also can obtain stable image quality for a long time.

In addition, according to this example, make the rotational speed of magnet drum be at least the speed of rotational speed more than 1.0 times of developing roller, use this velocity contrast, magnetic brush is contacted with developing roller, carry out the replacement of the toner on the developing roller, thereby can realize the effect of the replacement of toner exactly.

Below, be illustrated with regard to the structure of the developing parts that uses in this example.In Fig. 5, Fig. 6 although understand 4 kinds of developing parts, but effect is identical, to have used black to be representative with the developing parts 50A of toner, describes below.Fig. 9 is the sectional view of developing parts 50A, and Figure 10 is a section plan, and Figure 12 is a stereographic map, and Figure 13 is the figure of the example 1 of expression developing roller 2.

In the framework 12 that has formed コ word shape section, the developing roller 2 that left the given arranged spaced of photoreceptor 3, leave the given interval of this developing roller 2, disposed form with nonmagnetic material cylindric, and in cylinder, disposed a plurality of fixed magnets, had the magnet drum 1 of the sleeve that can around this fixed magnet, rotate.The axial width H of this sleeve ₃Axial width H than developing roller 2 ₁Long.

The 22nd, blade agitators has added bias voltage DC7a and AC7b between photoreceptor 3 and the developing roller 2, and DC8 is the bias voltage that is added on the magnet drum 1, and the 9th, the limiting scraper of the thickness of control magnetic brush, the 25th, toner sensor.

Below, with reference to Figure 12 and Figure 13, further describe the structure of developing roller 2.Among the developing roller 2A, become with conductor be the non magnetic sleeve that forms of aluminium cylinder 33, cooperate with the large-diameter portion of the flange 18 that forms by aluminium in a side's of this cylinder 33 end, the minor diameter of this flange 18 is supported by the bearing 28 that is formed by insulating component on developer container 12, just can rotate freely, contact and the lead of the top of this minor diameter by not showing among the figure links to each other with grid bias power supply portion 7 (Fig. 1).

And, on the outside surface 18a of flange 18, pasting the insulating thin 27 of PET (polyethylene terephthalate) system.In addition, between the outside surface 18a of flange 18 and the end of cylinder 33 at interval m, still, the end of cylinder 33 also can contact with outside surface 18a.

In addition, the gap roller 21 that has limited the interval between the surface of cylinder 33 of the surface of photoreceptor 3 and developing roller 2A can cooperate with the minor diameter of described flange 18 with rotating freely.

Another end of described cylinder 33 cooperates with the large-diameter portion of the flange 19 that is formed by aluminium, the minor diameter of this flange 19 is supported by the bearing 28 that is formed by insulating component on developer container 12, just can rotate freely, in addition, the gap roller 21 at the interval between the surface of the minor diameter of described flange 19 and the cylinder 33 of surface of having limited photoreceptor 3 and developing roller 2A can cooperate with rotating freely, and, stretch out to the outside from framework 12 on the top of the minor diameter of described flange 19, has fixed the driven wheel 29 that is used for obtaining from the drive source that figure does not show driving force in this top ends.

And, on the outside surface 19a of flange 19, pasting the insulating thin 27 of PET (polyethylene terephthalate) system, in addition, the minor diameter of described flange 19 also with the surface of the cylinder 33 of surface of having limited photoreceptor 3 and developing roller 2A between the gap roller 21 at interval can cooperate with rotating freely.

In addition, though described flange 19 is formed by conductive member, also can form by insulating component.At this moment, do not need insulating thin 17.

As mentioned above, because among the developing roller 2A, covered side one side of flange 18,19 by insulating component, even so side one side conductor of flange 18,19, can not make toner attached to this side one side owing to the magnetic brush 10 of magnet drum 1 yet, the toner that one side is adhered in the side can not be recovered to magnet drum 1 one sides, and toner can not disperse in machine.

Below, the magnet drum 1 in photoreceptor 3 and the developing parts 50 and the effect of developing roller 2 are described.

As Fig. 1, Figure 10 and shown in Figure 5, this processing element has developing roller 2 and the photoreceptor 3 of magnet drum 1, diameter 16mm.

This magnet drum 1 produces based on the magnetic brush that makes toner 5 carriers 4 charged, that also keep.In addition, by the toner that provides by magnetic brush 10, on the surface of developing roller 2, form toner thin layer 6.And photoreceptor 3 makes the toner of toner thin layer 6 circle in the air according to electrostatic latent image selectively, forms image.

In addition, kept the two-component developer that is made of toner 5 and carrier 4 on the surface of magnet drum 1, by stirrer 23 and blade agitators 22, developer is stirred on the limit, and the limit makes toner 5 with charged i.e. 5～20 μ c/g of proper level.Developer contacts with developing roller with certain layer thickness by limiting scraper 9.

The thickness of the toner thin layer on the developing roller 2 is set to 10～100 μ m, is preferably 35～70 μ m.When the mean grain size of toner was 7 μ m, this thickness was the value that is equivalent to 5 layers～10 layers of toner 5.

Gap between developing roller 2 and the photoreceptor 3 is 150～400 μ m, is preferably 200～300 μ m.If be lower than 150 μ m, can cause bluring, if be higher than 400 μ m, then be difficult to make toner 5 to fly on the photoreceptor 3, just can't obtain sufficient image color.In addition, become the reason of selecting development.

In order to have the effect of reclaiming and toner being provided, in developer, used specific insulation to surpass 10 ⁶Ω cm is lower than 10 ⁹The high resistance of Ω cm or insulativity carrier, by making the surface of magnetic brush 10 friction developing rollers 2, the toner 5 that static securely is attached on the bite of the carrier 4 that forms between developing roller 2 and the magnet drum 1 is peeled off, and the needed toner of development is offered developing roller 2.

At this moment,,, use the following minor diameter carrier of 40 μ m, increase magnetic brush 10, increase the surface area of carrier 4, a lot of toners 5 are delivered to developing roller 2 one sides in order to improve magnetic brush density in order to increase the contact point with toner 5.

In this example, carrier 4 is made of carrier core with magnetic and the coating that has comprised the High molecular weight polyethylene resin that polymerization forms on the surface of this carrier core, has used to have 10 ⁷～10 ⁸The resistance value of Ω cm, mean grain size are the ferrite carrier of 35 μ m, and, have the saturated magnetization of 60～100emu/g.At this, in the coating of carrier,, have and comprise water proofing property silicon dioxide, magnetic powder and or the layer of particulate resin at least as outermost layer.

Particularly, the carrier core has small concavo-convex in its surface, and coating is by kept polymerization catalyst in this is concavo-convex after, imports ethylene gas, and the weight average molecular weight Mw that generates behind the polymerization reaction take place is the High molecular weight polyethylene formation 50000 or more.

Therefore, just can realize high intensity and permanance.And if use this carrier, even use carrier repeatedly, the surface aging of carrier is also very little, just can form stable charged toner thin layer on developing roller.Its result just can correctly develop on photoreceptor.Because the permanance height of carrier, so before the mechanical life that reaches the development instrument, there is no need to change carrier in fact.

If 10 ⁶The resistance value that Ω cm is following, the low resistance carrier of paying attention to reclaiming is effective on correspondence development dual imaging, but make toner 5 correctly charged, keep in the development that does not have fuzzy generation just difficult, when long-term operation, toner disperses from the surface of developing roller, can make problems such as charged device and exposure component pollution.

In addition, if 10 ⁹The resistance value that Ω cm is above though can give chargeding performance, has the problem of charged easy rising.By the resistance value that makes carrier is appropriate value, just can reclaim the toner on the developing roller 2, just can put into charged exactly toner once again on the developing roller 2.

The blending ratio of the toner in this example is for the total amount of carrier and toner, and toner is 2～40 weight %, is preferably 3～30 weight %, is preferably 4～25 weight %.

If the blending ratio of toner is lower than 2 weight %, then the carried charge of toner raises, and can't obtain sufficient image color, if surpass 40 weight %, then can't obtain sufficient carried charge, toner disperses from developer, pollution image forms device inside, or forms fuzzy on image.

Because the potential difference (PD) Δ between magnet drum 1 and the developing roller 2, charged toner remains on the developing roller 2 with thin layer, by add with photoreceptor 3 between direct current with exchange overlapping bias voltage, develop.In order to prevent dispersing of toner, before developing, add interchange.

Special devices such as removing scraper plate need not be set, toner layer on the magnetic brush contact developing roller 2 on the magnet drum 1, based on the brush effect of the difference of each cylinder with based on the replacement of the developer of the magnetic brush of the stirring of stirrer, just can easily reclaim, replace toner.

As the method that is used to promote the replacement on the developing roller, the rotational speed of magnet drum 1 is set to 1.8 times of rotational speed of developing roller 2, reclaim the toner on the developing roller 2, and, just can form uniform toner layer by providing the developer that is set to appropriate toner concentration to developing roller 2.

In addition, in order to keep uniform developed concentration, the time beyond developing regularly, the potential difference (PD) Δ that makes 1 of developing roller 2 and magnet drum is idiostatic, do not causing under the prerequisite of burden to toner, very effective to the toner on the developing roller 2 is recovered on the magnet drum 1.

As the photosensitive material of photoreceptor 3, when using a-Si, have the low-down feature of exposure afterpotential below 10V on its surface, still, if its thickness attenuation, then the saturated zone electric potential descends, the withstand voltage decline of insulation breakdown.

On the one hand, the surface charge density of the photoreceptor 3 when forming latent image improves, the tendency that has developing performance to improve.In specific inductive capacity is about 10 high a-Si photoreceptor, when thickness below 25 μ m, be preferably in 20 μ m when following, this characteristic is remarkable especially.

In Fig. 1, be provided with by first direct current of the bias voltage Vdc1 that between photoreceptor 3 and developing roller 2, adds 0～200V with power supply unit 7a with exchange the power supply unit 7 that constitutes with power supply unit 7b.Exchange with power supply unit 7b and hold body (photoreceptor) 3, add the alternating voltage of crest voltage Vpp=500～2000V, frequency f=1～3kHz for the electrostatic latent image load.

In addition, be provided with second direct current power supply 8 of impressed voltage Vdc2 on magnet drum 1.And, determine the voltage of first and second direct current with power supply 7a and 8, make the potential difference (PD) of the current potential and the magnet drum 1 of developing roller 2 | the Vdc2-Vdc1|=Δ is 100～350V.At this, for example, Vdc2=250V, development bias voltage Vdc1 below the 150V, preferably is set to below the 100V.In addition, | Vdc2-Vdc1|=100～250V.And as the AC composition, Vp-p is 500～2000V, and frequency is 1～3KHz.

Magnetic brush 10 on the magnet drum 1 has limited layer by limiting scraper 9, because the current potential of developing roller 2 and the potential difference (PD) of magnet drum 1 | and the Vdc2-Vdc1|=Δ has formed the thin layer 6 that has only toner on developing roller 2.

The thin layer 6 of the toner on the developing roller 2 still also can be by described potential difference (PD) △ control owing to resistance or the current potential of developing roller 2 and the rotational speed difference of magnet drum 1 etc. of developer change.

If the raising Δ, thin layer 6 thickenings of the toner on the developing roller 2 then, if reduce Δ, then thin layer 6 attenuation.The scope of Δ generally at 100V to about the 250V.

At this, from test explanation bias voltage Vdc1 and potential difference (PD) | the relation of Vdc2-Vdc1| and development feature.

If bias voltage Vdc1 is higher than 200V, produce dual imaging.In addition, if potential difference (PD) | Vdc2-Vdc1| is lower than 100V, also produces dual imaging.

And if | Vdc2-Vdc1| is higher than 350V, produces fuzzy.

Therefore, bias voltage Vdc1 is at 0～200V (still, except 0V), and, potential difference (PD) | Vdc2-Vdc1| just can obtain high-quality image quality in the scope of 100～350V.

As using photoreceptor 3 in the image processing system, the OPC photoreceptor is just arranged all the time.But the photographic layer soft surface of OPC photoreceptor is because the friction of cleaning balde makes the photographic layer wearing and tearing easily.At this, compare with the OPC photoreceptor, the surface hard and aspect permanance and function retentivity (non-maintaining) superior performance, so what use in recent years is that the thickness of photographic layer is the a-Si photoreceptor of 25 μ m.But, because the a-Si photoreceptor is to use film forming such as electric glow discharge method, thus if photographic layer is thick like this, can cause manufacturing time long, the manufacturing cost height, very uneconomical.But, because the a-Si photoreceptor is to use film forming such as glow discharge decomposition method, thus if photographic layer is thick like this, can cause manufacturing time long, the manufacturing cost height, very uneconomical.

As photoreceptor 3, when the Organophotoreceptor that has used positively charged (OPC),, the film thickness of photographic layer is arranged on more than the 25 μ m in order to make rest potential below 100V, the addition that increases charge material is a particular importance.Because the OPC of single layer structure has added charge generating material in photographic layer, so even reduce the thickness of photographic layer, change of sensitivity is also little, be favourable.

At this moment, development bias voltage Vdc1 is arranged on below the 400V, is preferably below the 300V, can prevent from like this toner is added strong electric field.

If be provided with the development bias voltage lowly like this, not only can suppress the insulation breakdown of the a-Si photoreceptor of film, can also prevent the charged surplus of toner, suppress the generation of the hysteresis phenomenon of development effectively.In addition, on developing roller 2, form 10～100 μ m, be preferably the toner thin layer of 35～70 μ m, interval 150～400 μ m of developing roller 2 and photoreceptor, be preferably 200～300 μ m, because direct current and AC field make toner leap this space, arrive on the photoreceptor 3, thereby can form distinct image.

If referring again to Fig. 1, when image formed, the limit was stirred on the magnet drum 1 developer that is made of carrier 4 and toner that keeps, and the limit makes toner 5 charged with the level that is fit to, and developer forms magnetic brush 10.Then, by making this magnetic brush 10, with certain thickness contact contact developing roller 2 by limiting scraper 9.At this, the gap of limiting scraper 9 and magnet drum 1 is 0.3mm～1.5mm.

In addition, the gap of developing roller and magnet drum also is 0.3mm～1.5mm.

In addition, the gap of developing roller 2 and photoreceptor is 150～400 μ m, is preferably 200～300 μ m.

And the process linear speeds of developing roller 2 is 72mm/s, makes 1.8 times the speed rotation of magnet drum 1 with it.Its result owing to the brush effect based on difference, just can easily replace the toner of development remaining toner and supply.Therefore, not only suppress the generation of afterimage, and can form distinct image.

And, in this example, when a plurality of image of continuous formation, during the non-image formation before the development of arriving the next image of beginning behind the image developing, generation makes the surface potential of developing roller 2 and the equal equipotential state of surface potential of magnet drum 1.Then, under the equipotential state, join forces the remaining toner of the toner layer 6 on the Europe developing roller 2 with magnetic brush.

And, for example can detect according to the view data of printing during the non-image formation, for example in paper feeding cassette, also can detect from the top and the rear end of recording medium.

In this example, be equivalent to the interval of the recording chart during the non-image formation, promptly the rear end of the recording chart when paper supply to next open recording chart the top be spaced apart 51mm.Because the diameter of developing roller is 16mm, so its full girth is 16 π=50.27mm.Therefore, if be the equipotential state during whole during the non-image formation, the equipotential state at least can developing roller 2 revolve turn around during continue.

Below, in order to estimate the effect of this example, ask except in during the non-image formation from test, embodiment when the surface potential of developing roller and magnet drum is 0V, and make image color, the afterimage of the different comparative example of the surface potential of developing roller and magnet drum, the degree of fringe.

And, as shown in figure 11, the formation of magnet drum 1 axial width of formation toner thin layer of the sleeve axial width of magnetic brush and developing roller 2 all be H ₁, both relative height and positions do not stagger.

[embodiment]

In following embodiment, comparative example 1 and comparative example 2, carried out respectively forming based on the image of picture pattern shown in Figure 4.In this picture pattern, be configured to by the stereo-picture 13 of rectangle and then developing continuously of it than these stereo-picture 13 wide half tone images 16.

At this, the concentration of half tone image 17 be stereo-picture 13 concentration 25%.Why be 25% to be for than being easier to demonstrate dual imaging.

In the present embodiment, in above-described example, used the photoreceptor with a-Si photoreceptor 3 of thickness 14 μ m.

And when image formed, the surface potential that makes photoreceptor 3 was 200V, and the surface potential of developing roller 2 (Vdc1) is 50V, and the surface potential of magnet drum 1 (Vdc2) is 200V.

In addition, between photoreceptor 3 and developing roller 2, added frequency 24kHz, the alternating voltage of crest voltage 1.3kV.In addition, make 1.8 times the peripheral speed rotation of magnet drum 1 with the peripheral speed of developing roller 2.

And in the present embodiment, when non-image formation, the surface potential (Vdc2) of surface potential of developing roller 2 (Vdc1) and magnet drum 1 is 0V all, has produced equipotential state.

[comparative example 1]

In addition, in comparative example 1, during non-image formation, neither equipotential state, continue to add and identical bias voltage during image forms, formed image.

Promptly during non-image formation, the surface potential of developing roller 2 (Vdc1) is DC50V, and the surface potential of magnet drum 1 (Vdc2) is DC200V.

In addition, between developing roller 2 and photoreceptor 3, also added and identical alternating voltage during image forms.

And the development conditions beyond the bias voltage that adds during the non-image formation is identical with embodiment.

[comparative example 2]

In addition, in comparative example 2, during non-image formation in, bias voltage is put upside down, formed image.

Promptly during non-image formation, the surface potential of developing roller 2 (Vdc1) is DC200V, and the surface potential of magnet drum 1 (Vdc2) is DC50V.

And the development conditions beyond the bias voltage that adds during the non-image formation is identical with embodiment.

And, confirmed the evaluation result that the image that carries out with the development conditions of the above embodiments, comparative example 1, comparative example 2 forms, i.e. concentration, afterimage and fuzzy generation in initial, three phases such as the 100th, the 1000th.

And, in any one of initial, three phases such as the 100th, the 1000th, all there not be to find bluring on concentration, afterimage and fuzzy generation, just can form preferable image.

In contrast to this, in comparative example 1, because all adding same bias voltage during the non-image formation and during forming image, so accumulated afterimage gradually.Its result at the 100th, can observe afterimage a little, and the 1000th stage, just can clearly confirm afterimage.

In addition, in comparative example 2, because make the potential difference (PD) during the non-image formation take place to put upside down, though can suppress the generation of afterimage, the charged variation of toner takes place fuzzy, the 100th stage, can observe fuzzyly a little, and, just can clearly confirm to blur the 1000th stage.

Therefore, from described result as can be known,, just can avoid the generation of bluring, just can suppress the generation of afterimage, thereby can form distinct image by during non-image formation, taking the equipotential state.

Then, as shown in figure 11, the formation of magnet drum 1 the sleeve axial width H of magnetic brush ₃Axial width than the formation toner thin layer of developing roller 2 all is H ₁At the long 0.5mm of a side, form the image of the half tone image 17 shown in Figure 17 (a), carried out tests initial, 100,1000, in the stage arbitrarily, do not take place that concentration is fuzzy, afterimage, fuzzy, just can form preferable image. Development remaining toner 15a, 15b, 15c are by the carrier 24C of magnetic brush ₂, 24C ₃, 24C ₄Reclaimed.

In addition, in above-described example, when during making non-image formation, being the equipotential state, the surface voltage that makes developing roller and magnet drum all is 0V, but, as long as it is just passable as the equipotential state surface voltage of developing roller and magnet drum to be equal to each other, not necessarily will make two surface voltages is 0V.For example, when the equipotential state, can make the surface voltage of developing roller and magnet drum be respectively 50V.

In addition,, can realize, in addition, also can make the surface potential of a side and equating of opposite side by control by two surface potentials of control developing roller and magnet drum in order to realize the equipotential state.

As mentioned above, just can provide to have prevented dispersing of toner, and, develop with low electric field, just can on developing roller, not stay the development hysteresis phenomenon, have the image processing system of good toner recovery property.

In addition, because magnetic brush forms regional H ₃Be the width that is used to reclaim toner on the developing roller 2, so by making the width H of developing roller 2 ₁Form regional H than magnetic brush ₃Short, just can eliminate not recovery zone exactly.

In view of the above, no longer include, the dispersing of toner of two ends can not taken place attached to the toner on the developing roller sleeve beyond the magnetic brush zone.

In addition, when image forms, because the potential difference (PD) that forms between described developing roller and the magnet drum, on described developing roller, formed toner thin layer, when non-image formation, remaining toner on the described developing roller is under 0 the state in described potential difference (PD), and the magnetic brush with described magnet drum of the peripheral speed faster than described developing roller reclaims.And, faster by the peripheral speed that makes magnet drum than the peripheral speed of developing roller, except increasing the chance that magnetic brush contacts with developing roller, and improved based on the shear stress of magnetic brush, the remaining toner on the developing roller is worked, just can weaken remaining toner on the developing roller to the contact pressure of developing roller, even externally-applied potential is not poor between developing roller and magnet drum, under equipotential, because high magnetic carrier just can reclaim remaining toner effectively.

Below, with reference to Figure 14, be illustrated with regard to other examples of developing roller.The example 1 of Figure 13 is with the different of this example 2: the brush in the example 1 has used conductor component, is pasting insulating tape in its side, and in this example 2, is forming flange with insulating component.

As shown in figure 14, among the developing roller 2B of this example 2, with conductor is that a side's of the cylinder 33 that forms of aluminium end cooperates with the large-diameter portion of the flange 38 that is formed by POM (polyacetal) material, the interval that m (about 1mm) arranged between the end face of cylinder 33 and the flange 38b, the minor diameter of this flange 38 is by being supported by metal bearing 48 on framework 12, just can rotate freely, stretch out from framework 12 on the top of this minor diameter, and, 2B axially on be provided with hole 38a, disposed the bias terminal 30 of spring material in the 38a of this hole, contact and lead by not showing among the figure link to each other with grid bias power supply portion 7 (Fig. 1).This bias terminal 30 contacts with the inside surface of the cylinder 33 that has formed circular contact in cylinder 33.

And the gap roller 21 that has limited the interval between the surface of cylinder 33 of the surface of photoreceptor 3 and developing roller 2B can cooperate with the minor diameter of described flange 38 with rotating freely.

Another end of described cylinder 33 cooperates with the large-diameter portion of the flange 39 that is formed by the POM material, the interval that m (about 1mm) arranged between the end face of cylinder 33 and the flange 39b, the minor diameter of this flange 39 is by being supported by metal bearing 48 on framework 12, just can rotate freely, stretch out from framework 12 on the top of this minor diameter.

In addition, the gap roller 21 that has limited the interval between the surface of cylinder 33 of the surface of photoreceptor 3 and developing roller 2B can cooperate with the minor diameter of described flange 39 with rotating freely, and, fixed the driven wheel 29 that is used for obtaining driving force from the drive source that figure does not show on the top of described minor diameter.

According to this example, as mentioned above, because developing roller 2B has formed flange 38,39 with insulating component, so can not make side one side of toner owing to the magnetic brush 10 of magnet drum 1 attached to flange 38,39, the toner that one side is adhered in the side can not be recovered to magnet drum 1 one sides, and toner can not disperse in machine.

Therefore, according to present embodiment, because the axial magnetic brush that forms in magnet drum one side forms regional than forming the zone greatly at the surperficial axial toner thin layer that forms of developing roller, so can form the abundant toner thin layer zone that covers the electrostatic latent image zone that form on the photoreceptor on the developing roller surface of correspondence.

In addition, when non-image formation, because the axial magnetic brush that forms in magnet drum one side forms regional than forming the zone greatly at the surperficial axial toner thin layer that forms of developing roller, so can fully have been covered the toner thin layer zone in the electrostatic latent image zone that forms on the photoreceptor in developing roller one side, when image forms, the supply of the toner in the outside of the Width in the electrostatic latent image zone that forms on photoreceptor can be abundant, just can form image fully, and, the insufficient and afterimage phenomenon of the recovery of the remaining toner on the developing roller can not take place.

In addition, toner can not prevent dispersing of this toner attached to developing roller side one side, just can form good picture.

Below, according to Fig. 1, Figure 18, Figure 19, be illustrated with regard to example 2 of the present invention.And Figure 18 is used to illustrate developing method of the present invention, has represented the curve map of relation of the rotation number of the potential difference (PD) of magnet drum and developing roller and developing roller; Figure 19 is expression developing method of the present invention and the curve map based on the formation situation of the toner layer of the number of revolutions of developing roller in the developing method in the past.

In this example, the value of the bias voltage DC31a of the magnet drum by making Fig. 1 is variable, as Figure 18 30 shown in, the potential difference (PD) that is provided with the potential difference (PD) Δ of developing roller 2 in the first lap that begins to develop later on than second circle is big.As the value of this potential difference (PD) Δ, as mentioned above, just can in the scope of 250V, be provided with at 100V, still, when the reference potential difference is set to 150V, the potential difference (PD) Δ of developing roller 2 in the first lap that begins to develop is about+50V (+45V～55V).If be provided with excessive potential difference (PD), then the toning dosage on the developing roller increases, and causes dispersing of toner.In addition, if discontented 45V just can't obtain significant effect.

Promptly as Figure 18 31 shown in, when the later potential difference (PD) of the potential difference (PD) Δ in the first lap that developing roller 2 is beginning to develop and second circle is identical, as Figure 19 41 shown in, even the rotation number of developing roller 2 has reached 2 circles, on developing roller 2, do not have formation to obtain the necessary toning dosage 42 of uniform development yet, thereby produced the density loss in afterimage shown in Figure 4 and the continuous printing.This phenomenon is because inhomogeneous the causing of toner on the back developing roller that develops, but this example is such as described, by making the potential difference (PD) Δ of developing roller 2 in the first lap that begins the to develop potential difference (PD) later big than second circle, as Figure 19 40 shown in, just can just can make the bed thickness of toner certain from developing roller 2 rotation first laps.

And rise, in this example, behind the image developing when making a plurality of image of continuous each processing element of formation to the beginning next image development before non-image formation during or begin to form image before be provided with arbitrarily in the time, make described developing roller 2 and magnet drum 1 and blade agitators 22 keep rotation, generation makes the surface potential DC31a of developing roller 2 and magnet drum 1 and the equipotential state that DC30a equates, and, under these potential states, reclaim development remaining toner on the described developing roller 2 with magnetic brush.And, can be not only when forming a plurality of image continuously during this non-image formation, also can be before beginning to form image, for example the control circuit that from figure, does not show transmit the signal that begins to print begin to recording medium delivered to from paper feeding cassette 53 between the travelling belt 54 during.The printed image data that for example can transmit the signal that begins to print according to the control circuit that does not show from figure, sends exposer 57 to detects during this non-image formation, also can be in paper feeding cassette 53, from the top and the rear end detection of recording medium.

And, for the equipotential state of the surface potential of developing roller 2 and magnet drum 1, because as long as | DC31a-DC30a| (Δ) is that 0V is just passable, is 0V or 50V so for example make two current potentials, can be current potential arbitrarily.In addition, these potential states can be realized by two surface potentials of control developing roller 2 and magnet drum 1, also can make the surface potential of a side and equating of opposite side by control, also can not be to be the equipotential state during whole during the non-image formation, can be to be the equipotential state in during the part.

Like this, by during non-image formation or before beginning to form image, make developing roller and magnet drum and blade agitators keep rotation, the equipotential state that generation equates surface potential, toner has been disappeared attached to the electrostatic force on the developing roller, and its result is by the magnetic brush effect based on the difference of developing roller and magnet drum, just can not cause burden, efficiently the development remaining toner is recovered on the magnet drum to toner.Therefore, just can easily reclaim the development remaining toner of the reason that becomes afterimage, avoid fuzzy generation, suppress the generation of afterimage, thereby can form distinct image.

And, in this example, the magnetic brush that forms on the magnet drum 1 contacts with developing roller 2, just can be recovered in the development of the latent image on photoreceptor 3 in the thin layer that has only toner on the developing roller 2 the untapped toner remaining toner that promptly develops with the brush effect that produces based on the difference of each cylinder.And, get this magnetic brush by scraping with the blade of blade agitators 22, just can mix the toner that reclaims with the magnetic brush of this magnet drum 1 with new developer, by the developer of this mixing is offered developing roller 2 once more, special devices such as removing scraper plate need not be set, just can easily carry out the recovery and the replacement of toner.

As the carrier that uses in the developing parts of implementing this example, having used specific insulation is 10 ⁷The ferrite carrier of Ω cm, saturated magnetization 70emu/g, mean grain size 35 μ m.As strong magnetic force and low-resistance carrier, magnetic iron ore carrier, Mn class ferrite, Mn-Mg class ferrite etc. are arranged, can intactly use these carriers, also can be in the scope that does not improve resistance, it is carried out surface treatment after, re-use.This carrier has the development remaining toner that reclaims on 2 and supplying with the effect of toner thereafter, if resistance value is 10 ⁶Ω cm～10 ⁹Carrier in the scope of Ω cm just can be peeled off the toner of firm electrostatic adhesion on the bite between developing roller 2 and the magnetic brush 1 with magnetic brush, and the necessary toner that develops just can be provided.

At this moment,, preferably use the following minor diameter carrier of 40 μ m, improve the surface area of carrier in order to increase the contact point with toner.If 10 ⁶The resistance value that Ω cm is following, on the development dual imaging on the corresponding developing roller 2, be effective, but make toner 5 correctly charged, keeping does not have fuzzy generation aspect just difficult, when long-term operation, toner disperses from the surface of developing roller, can make problems such as charged device and exposure component 57 pollutions.In addition, if 10 ⁹The resistance value that Ω cm is above though can give chargeding performance, has the problem of charged easy rising.By the resistance value that makes carrier is appropriate value, just can reclaim the toner on the developing roller 2, just can put into charged exactly toner once again on the developing roller 2.

And be controlled at 5～20 μ C/g by the toner carried charge, just can provide to prevent that toner from dispersing, bluring, and, by under low electric field, developing, on developing roller 21, do not stay the development hysteresis phenomenon, have the toning system that good toner reclaims property.Charged toner forms magnetic brush with carrier on magnet drum 1, by the potential difference (PD) between magnet drum 1 and the developing roller 2 | DC31a-DC30a| (Δ), on developing roller 2, form thin layer, by and photoreceptor 3 between direct current, the overlapping bias voltage of interchange, charged toner flies on the photoreceptor 3, makes developable latent image.At this moment, by the magnetic brush that forms is contacted with toner layer on the developing roller 2, the brush effect that produces with the difference of each cylinder, reclaimed the development remaining toner on the developing roller 2, stirring by blade agitators 22, special devices such as removing scraper plate need not be set, just can easily carry out the recovery and the replacement of toner.

The blending ratio of the toner in this example is for the total amount of carrier and toner, and toner is 2～40 weight %, is preferably 3～30 weight %, is preferably 4～25 weight %.If the blending ratio of toner is lower than 2 weight %, then the carried charge of toner raises, and can't obtain sufficient image color, if surpass 40 weight %, then can't obtain sufficient carried charge, toner disperses from developer, pollution image forms device inside, or forms fuzzy on image.

In addition, in order to promote the replacement of developer, in this example, make the speed of the rotational speed of magnet drum 1 faster than developing roller 2, and, be set to developing roller 2 rotational speed less than 2 times, not only reclaim the toner on the developing roller 2, and offer developing roller 2 by the developer that is set to appropriate toner concentration, just can form uniform toner layer.

When having used the Organophotoreceptor (OPC) of positively charged as photoreceptor 3, development bias voltage DC7a is below the 500V, is preferably disposed on below the 400V, this means can prevent to add highfield to toner.

If be provided with the development bias voltage lowly like this, not only can suppress the insulation breakdown of the a-Si photoreceptor of film, can also prevent the charged surplus of toner, suppress the generation of the hysteresis phenomenon of development effectively.In addition, on developing roller 2, form 10～100 μ m, be preferably the toner thin layer of 35～70 μ m, interval 150～400 μ m of developing roller 2 and photoreceptor 3, be preferably 200～300 μ m, because direct current and AC field make toner leap this space, arrive on the photoreceptor 3, thereby can form distinct image.

And the gap of limiting scraper 9 and magnet drum 1 is 0.3mm～1.5mm, and the gap of magnet drum 1 and developing roller 2 also is about 0.3mm～1.5mm, and the toner thin layer on the developing roller 2 is 6～100 μ m, is preferably 30～70 μ m.When the mean grain size of toner was 7 μ m, this thickness was the value that is equivalent to 5 layers～10 layers of toner.In addition, the gap of developing roller 2 and photoreceptor 3 is 150～400 μ m, is preferably 200～300 μ m.If narrower than this gap, will cause bluring, if be wider than 400 μ m, just be difficult to make toner to fly on the photoreceptor 3, thereby can't obtain sufficient image color.In addition, composition makes the reason of selecting development to take place.

Use forms the developing parts of the evaluation machine of device based on tandem type image shown in Figure 5, with processing speed 84mm/sec, 14/minute speed, prints, and has estimated the developing method of this example.30 of Figure 18 has represented the magnet drum 1 of this moment and the model of the potential difference (PD) Δ between the developing roller 2, Figure 19 40 in represented the weight of the toner on the developing roller 2 of this moment.In order to suppress the dual imaging that develops, even carry out the printing of high concentration, also can keep stable concentration, when the toner thin layer of the development that on developing roller 2, is formed for the latent image on the photoreceptor, as Figure 19 42 shown in, be necessary to begin just to guarantee 1.0mg/cm from the first time of the rotation number of developing roller ²Above toner in this example, just can begin just to guarantee 1.0mg/cm from first lap ²Above toner, thus can carry out stable printing.

If promptly use the developing method of this example, the first lap that rotates from developing roller 2 begins just can obtain the necessary toner amount, is accompanied by this, just can prevent the generation of afterimage shown in Figure 4.Promptly in the developing method of this example, it is such can not go out phenomenon developing method in the past, make developing roller idle running in the timing of developing, maybe can't guarantee to develop fully interval etc., do not worry for the load increase of developer or the charged deterioration of toner, print speed printing speed can not take place yet descend, do not worry the decline based on the development of selecting to develop.In view of the above, even when carrying out the printing of coloured image and black white image mixing, also can guarantee development amount of all kinds, just can keep good development.

From above explanation as can be known, according to this example, although be the small-sized colored machine of tandem, by in the developing parts of mixed type, the potential difference (PD) of control developing roller and magnet drum just can form uniform toner layer on developing roller.In addition, there is not potential difference (PD) in the timing by beyond development of all kinds, just can suppress to develop to lag behind, and just can make the charged stable of toner, thereby can obtain distinct image.In view of the above, even when carrying out the printing of coloured image and black white image mixing, also can guarantee development amount of all kinds, just can keep good development.

Promptly according to this example, when the toner thin layer of the development that on developing roller, is formed for the latent image on the photoreceptor, potential difference (PD) when forming by a toner thin layer at first lap between first and second Dc biases is provided with greatlyyer than the potential difference (PD) when the later toner thin layer of second circle forms, just can prevent, such in the past, when the potential difference (PD) between first and second Dc biases first lap and second the circle after all mutually produced simultaneously enter second the circle development the time, the toning dosage phenomenon different of the toner layer on the developing roller with first lap, and after the development of high concentration, absolute magnitude at the later toner of second circle becomes not enough, causes the phenomenon of density loss.When developing, not only can just can guarantee the toner layer of necessary amount from the first lap of developing roller, and, even after having carried out the development of high concentration, also can be sufficient in second absolute magnitude of enclosing later toner, can not cause density loss.

Therefore, the generation of the afterimage in the time of preventing to develop continuously just can be provided, for developing roller provides charged exactly toner, can not cause the dosage difference of mixing colours, or image color descends, can keep the control method of the mixed type developing parts of stable image quality for a long time, in view of the above, just can be with the small-sized series connection image processing system of low price composing images stay in grade.

And, according to this example, when the potential difference (PD) that makes the first lap that is provided with later on greatlyyer than the second circle potential difference (PD) big 50V later than second circle is above, toning dosage on the developing roller increases, it is the reason that causes toner to disperse, in addition, when being discontented with 50V, just can not get significant effect, by being arranged on about about 50V, just can prevent such phenomenon, when described development, begin just to have guaranteed the toner layer of necessary amount from the first lap of developing roller, and, even after the development of having carried out high concentration, the absolute magnitude deficiency of toner also can not appear, can not cause the decline of image color.

And, according to this example, by during non-image formation, make developing roller and magnet drum keep rotation, the state that generation equates the potential difference (PD) between first and second Dc biases, and, by only adding described AC bias, special devices such as removing scraper plate need not be set, or causing burden to toner, the magnetic brush on the magnet drum contacts with toner layer on the developing roller, just can reclaim the residual toner of development by the brush effect based on the difference of each cylinder, and, just can carry out replacing based on the developer of the stirring of using stirrer.Therefore, just can easily reclaim the residual toner of development that causes afterimage, avoid the generation of bluring, suppress the generation of afterimage, thereby can form the image of distinctness.

Below, other examples of the present invention that are provided with the toner replenishing control device are described.

Shown in Figure 10,20, on developing parts,, be provided with toner container 24 across supply cylinder 25 on the top of developer container 12, on the developer container wall relative, be provided with toner sensor 71 in addition with stirrer 23 in the developer container.

This toner sensor 71 is installed on the developer container 12.And this toner sensor 71 links to each other with control part (CPU) 72.As described later, CPU72 drive controlling toner motor 73 makes supply cylinder 25 rotation, from toner container 24 to developer container 12 supply toners.

But, as shown in Figure 5, when making 55 exposures of photoreceptor magnetic drum with exposure component 57, promptly when driving exposure component 57, provide the exposure component drive signal to exposure component 57.For example, (CCD: do not show among the figure) reads original copy with scanner, exports as picture signal (view data).As everyone knows, the performance of this view data is dot matrix, is sent to exposure component 57 based on the exposure component drive signal of view data, and according to this view data, photoreceptor magnetic drum 55 is exposed.And in illustrated embodiment, view data has been passed to CPU72.The number count signal of expression printing number is provided to CPU72.

At this, with reference to Figure 21, if start image processing system (step S1) now, then CPU72 is with Mode A work (step S2).In Mode A, as mentioned above, CPU72 controls the open and close of toner motor 23 according to the toning dosage detection signal that transmits from toner sensor 71.In a word, the toning dosage that toner sensor 71 monitors in the developer container 12 if the toner quantitative change in the developer container 12 must be lower than predetermined amount, sends low level signal.At CPU72,, just make 73 work of toner motor if receive low level signal.In view of the above, supply cylinder 25 rotation, with given interval, from toner container 24 to developer container 12 supply toners.If the toner quantitative change in the developer container 12 must be higher than more than the scheduled volume, toner sensor 71 just sends high level signal.At CPU72,, just turn off toner motor 73 if receive high level signal.In view of the above, stop from toner container 24 to developing apparatus supply toner.Like this, under Mode A, just can almost be controlled to be scheduled volume to the toning dosage in the developer container 12.

As mentioned above, provide expression to print the number count signal of number to CPU72, CPU72 learns the printing number from the number count signal.And if the printing number surpasses predetermined number (for example 500) (step S3), CPU72 just enters Mode B (step S4).

After entering Mode B, regardless of the dosage detection signal of mixing colours, CPU72 stops toner replenishing.Then,,,, measure its image density, obtain measuring image density (Wt) according to counting of view data for each view data (i.e. the original copy density of a paper used for recording) at CPU72.At CPU72, totally measure image density successively, as accumulative total image density (∑ Wt).For example, CPU72 obtains accumulative total image density (∑ Wt) according to accumulative total image density (∑ Wt)=(measuring image density * printing number).Whether CPU72 judgement accumulative total image density has surpassed the value (α) that sets in advance, and (step 5) if the accumulative total image density has surpassed the value that sets in advance, then enters step S1, works under Mode A.

As mentioned above, from the mensuration image density of counting of view data, this measures image density accumulative total, obtains the accumulative total image density, and before this accumulative total image density surpassed the value that sets in advance, the supply toner stopped then.In other words, predesignate the relation of accumulative total image density and consumption of toner, according to the accumulative total image density, the prediction consumption of toner.Promptly at CPU72, measure the image density of each paper used for recording according to view data, the image density that accumulative total is measured obtains the accumulative total image density, according to this accumulative total image density, the consumption of prediction toner.Then, CPU72 forbidding in the time before toner reaches specified rate, forbid the supply of toner.Therefore, near the toner (toner that particle diameter is big and old toner) the developing roller 2 is consumed.

And, when Mode B, when non-image formation, be fit to make the toner on the developing roller 2 to move on the photoreceptor magnetic drum 55, the action of reclaiming with the clearer that does not show among the figure is so-called false development the (for example, average character-display unit is when set-point is following).

Can easily understand from above explanation, execution pattern B (pattern of forbidding the supply of toner) time span is by accumulative total image density (∑ Wt)=(measuring image density * printing number) decision, if stipulate execution pattern B time span like this, then irrelevant with the mensuration image density, the fluctuation that just can control the toning dosage in the developer container 12 is (at this, the fluctuation of toning dosage is meant that (1) almost is controlled to be toning dosage in the developer container 14a of scheduled volume at the slip of Mode B under Mode A, or (2) for the toning dosage in the developer container 14a that almost is controlled to be scheduled volume under Mode A, and near the toning dosage the sleeve 14c is in any one of the slip of Mode B).In a word, if only with printing number regulation execution pattern B time span, then when the mensuration image density was low, near the consumption of the toner developing roller 2 was few, and the fluctuation of toning dosage diminishes.If the image density height, near the consumption of the toner developing roller 2 increases, and the fluctuation of toning dosage becomes big (being that near developing roller 2 toning dosage reduce).Its result does not form toner thin layer sometimes on developing roller.

At this, with reference to Figure 22, carried out in the past toner replenishing control (example in the past) and the image color passing during with the toner replenishing control (this supply control) of Figure 21 explanation.In Figure 22, the curve of representing with ◇ is routine in the past, and the curve of representing with ■ is this supply control.As can be seen from Figure 22, in example in the past, if the printing number surpasses 7kpage to 8kpage (7000 to 8000), image color just descends rapidly, and in this supply control, even the printing number surpasses 30kpage (30000), image color is also stable.If promptly use this supply control, the stability of image color has increased.

With reference to Figure 23, near the passing of the toner mean grain size (μ m) of (for example, the developing roller) in the developer container 14a when having carried out routine in the past and this supply control is described.In Figure 23, the curve of representing with ◇ is routine in the past, and the curve of representing with ■ is this supply control.As can be seen from Figure 23, in example in the past, begin printing back (the printing number is about 1kpage to 2kpage), the toner mean grain size significantly rises, also continue then to rise, even crossed 5kpage, and the also earthquake of toner mean grain size.And in this supply control, begin printing after, though the toner mean grain size rise, surpassed 5kpage from the printing number near, the last mean grain size of cosmetics is stably passed.And in example and this supply control in the past, there is a big difference on the toner mean grain size (in this supply control, the toner mean grain size is more routine little more a lot of than in the past).

As previously discussed,, produced fluctuation on the toning dosage in the developer container 14a, caused resupplies to move at short notice near the toner the developing roller 2 if carry out the toner replenishing control of Figure 21 explanation.Its result, old toner (toner that particle diameter is big and the toner of deterioration) is consumed, and new toner is provided near the developing roller 2, thereby can prevent the decline of image color and fuzzy effectively.

And according to inventor's etc. test, the toner stability bandwidth is for the toning dosage of developer container 14a, is preferably in 5 to 50% the scope.If the toner stability bandwidth is lower than 5%, then be difficult to avoid select to develop, and if the toner stability bandwidth surpasses 50%, then toner replenishing forbid that the time is elongated, be difficult on the developing roller 2 and form toner thin layer.

In addition, in example illustrated in fig. 21, illustrated and begun printing, if the printing number has surpassed the number of predesignating (for example 500), then CPU72 transfers to the example of Mode B from Mode A, but become when being lower than the concentration of predesignating when measuring image color, CPU72 also can transfer to Mode B from Mode A.In a word, before the image color of predesignating produced decline, CPU72 also can transfer to Mode B from Mode A.

Therefore, in example of the present invention, the image density that accumulative total obtains from view data, forbid the supply of toner according to this accumulated result, so old toner is used consumption, and new toner is provided to developer load and holds near the body, can prevent that image color from descending and fuzzy etc. effect thereby have.

And, in example of the present invention, do not carry out the false decline that just can prevent image color and blur etc. of developing, consequently can also prevent the waste of toner.

Claims (19)

1. image processing system, comprise at least one insulation by magnet drum or high-resistance toner and based on the magnetic brush of carrier, utilization is formed on the outer lip-deep toner thin layer of developing roller that is added with the development bias voltage, the developing parts that electrostatic latent image on the photoreceptor is developed is characterized in that:

Be formed with axial toner thin layer and form the zone on the surface of described developing roller, it is little to make it to form the zone than the axial magnetic brush that is formed on described magnet drum one side.

2. image processing system according to claim 1 is characterized in that:

Form the two ends in zone at described toner thin layer, the non-toner thin layer that forms insulation or the high resistance area higher than toner resistance forms the zone.

3. image processing system according to claim 1 is characterized in that:

When image forms, because the potential difference (PD) that between described developing roller and magnet drum, forms, and on described developing roller, formed toner thin layer; When non-image formation, the remaining toner on the described developing roller is under 0 the state in described potential difference (PD), and the magnetic brush with described magnet drum of the peripheral speed also faster than the peripheral speed of described developing roller reclaims.

4. image processing system according to claim 1 is characterized in that:

150～400 μ m that are set between described photoreceptor and the developing roller, and when image formed, from described magnet drum, forming thickness on described developing roller was 5～10 times toner thin layer of toner mean grain size.

5. image processing system according to claim 1 is characterized in that:

The mean grain size of carrier is set to 3～9 times of toner mean grain size.

6. image processing system according to claim 1 is characterized in that:

Development bias voltage between described magnet drum and the developing roller is set to 100V～250V, and forming thickness on described developing roller is 5～10 times toner thin layer of toner mean grain size.

7. described image processing system of claim 1, the development bias voltage that described development bias voltage is an overlapping AC bias on first Dc bias, the bias voltage that adds on the described magnet drum is second Dc bias, it is characterized in that:

When the toner thin layer of the development that is formed for the latent image on the photoreceptor on described developing roller, the described difference the when toner thin layer that the difference between described first and second Dc biases when toner thin layer at first lap is formed is provided with later on than second circle forms is big.

8. image processing system according to claim 7 is characterized in that:

Make difference between first and second Dc biases of described first lap than the later big 45～55V of described difference of second circle.

9. image processing system according to claim 7 is characterized in that:

Before and after image forms and image forms and image next time form between or during the non-image formation between the recording medium when forming image continuously etc., described developing roller and magnet drum are kept under the state of rotation, it is 0 equipotential state that generation makes difference between described first and second Dc biases, only add simultaneously described AC bias, and replace toner on the described developing roller with described magnetic brush and AC bias.

10. described image processing system of claim 1, the development bias voltage that described development bias voltage is an overlapping AC bias on first Dc bias, the bias voltage that adds on the described magnet drum is second Dc bias, it is characterized in that:

Before and after image forms, image forms and image next time form between, any one party or two sides during the non-image formation between the recording medium when forming image continuously etc., described developing roller and magnet drum are kept under the state of rotation, the equipotential state that generation equates described first and second Dc biases, only add simultaneously described AC bias, and replace toner on the described developing roller with described magnetic brush and AC bias.

11. image processing system according to claim 10 is characterized in that:

The AC bias that adds on described developing roller is set at square wave, when using the positively charged toner, makes positive dutycycle, when using electronegative toner, make negative dutycycle less than 45% less than 45%.

12. image processing system according to claim 10 is characterized in that:

When being between the recording medium time during the described non-image formation, it is longer than the processing girth of described developing roller to control the length that makes between this recording medium.

13. image processing system according to claim 10 is characterized in that:

Make the rotational speed of described magnet drum be at least 1.0 times speed above the rotational speed of developing roller, and, two cylinders are rotated in the forward, make magnetic brush contact developing roller with this velocity contrast, carry out the replacement of the toner on the developing roller.

14. the described image processing system of claim 1 has to the supply parts of the described developer of the described developing parts supply of claim 1 and the control assembly of the described supply parts of control, it is characterized in that: described control assembly has:

Measure the image density of each paper used for recording according to described view data, this image density of accumulative total obtains the integrating block of accumulative total image density;

Infer the supposition parts of the consumption of described developer according to described accumulative total image density;

Forbidding in the time before described consumption reaches specified rate, forbid the parts of forbidding based on the supply of the described developer of described supply parts.

15. image processing system according to claim 14 is characterized in that:

Described integrating block is obtained described accumulative total image density according to described image density * printing number.

16. the described image processing system of claim 1 has to the supply parts of the described developer of the described developing parts supply of claim 1 and the control assembly of the described supply parts of control, it is characterized in that: described control assembly has:

Measure the image density of each paper used for recording according to described view data, this image density of accumulative total obtains the integrating block of accumulative total image density;

Forbidding in the time before described accumulative total image density reaches the value of predesignating, forbid the parts of forbidding based on the supply of the described developer of described supply parts.

17. the described image processing system of claim 1 has to the supply parts of the described developer of the described developing parts supply of claim 1 and the control assembly of the described supply parts of control, it is characterized in that: described control assembly has:

The amount of the described developer in the described developing parts is detected as detecting developer level, if this detection developer level is lower than predetermined amount, just control described supply parts, to the supply control assembly of the described developer of described developing parts supply;

Measure the image density of each paper used for recording according to described view data, this image density of accumulative total, obtain the accumulative total image density, infer the consumption of described developer according to described accumulative total image density, forbidding in the time before described consumption reaches specified rate, forbid the control assembly of forbidding based on the supply of the described developer of described supply parts.

18. the described image processing system of claim 1 has to the supply parts of the described developer of the described developing parts supply of claim 1 and the control assembly of the described supply parts of control, it is characterized in that: described control assembly has:

The amount of the described developer in the described developing parts is detected as detecting developer level, if this detection developer level is lower than predetermined amount, just control described supply parts, to the supply control assembly of the described developer of described developing parts supply;

Measure the image density of each paper used for recording according to described view data, add up this image density and obtain the accumulative total image density, forbidding in the time before described accumulative total image density reaches the value of predesignating, forbid the control assembly of forbidding based on the supply of the described developer of described supply parts.

19. image processing system according to claim 18 is characterized in that:

The described control assembly of forbidding is obtained described accumulative total image density according to described image density * printing number.

Images